[Misc] A hodgepodge of tiny changes

CMake:
  Simplify cmake target+version config generation and make it actually
  work.  With the changes it is now possible to detect and use
  `Notcurses` in the following way:

     find_package(Notcurses REQUIRED)
     ...
     target_link_libraries(myapp PRIVATE notcurses::notcurses)

  Also, added the same CMake configuration for `Notcurses++`, to be used
  in the following way:

     find_package(Notcurses REQUIRED
     find_package(Notcurses++ REQUIRED)
     ...
     target_link_libraries(myapp PRIVATE notcurses++::notcurses++)

Docs:
  `notcurses_cell(3)`: `cell_styles_{on,off} -> cell_{on,off}_styles`
  and `cell_load_simple` -> `cell_load_char`

C++ API:
  * Plane: added constructors taking `ncplane_options const&` instead of
    the multitude of individual parameters
  * Plane: drop `struct` when `ncplane_options` is used.
  * Plane: added `strdup` (`cell_strdup`)
  * Plane: added `extract` (`cell_extract`)

CMakeLists.txt

@@ -601,23 +601,47 @@ include(CMakePackageConfigHelpers)
 configure_file(tools/version.h.in include/version.h)
 configure_file(tools/builddef.h.in include/builddef.h)
 
-configure_package_config_file(tools/NotcursesConfig.cmake.in
-  ${CMAKE_CURRENT_BINARY_DIR}/NotcursesConfig.cmake
-  INSTALL_DESTINATION ${CMAKE_INSTALL_PREFIX}/lib/notcurses/cmake
-)
-
 write_basic_package_version_file(
   ${CMAKE_CURRENT_BINARY_DIR}/NotcursesConfigVersion.cmake
   COMPATIBILITY SameMajorVersion
 )
 
+write_basic_package_version_file(
+  ${CMAKE_CURRENT_BINARY_DIR}/Notcurses++ConfigVersion.cmake
+  COMPATIBILITY SameMajorVersion
+  )
+
 # Installation
 install(FILES
-  "${CMAKE_CURRENT_BINARY_DIR}/NotcursesConfig.cmake"
   "${CMAKE_CURRENT_BINARY_DIR}/NotcursesConfigVersion.cmake"
   DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/Notcurses"
 )
 
+install(TARGETS notcurses
+  EXPORT "NotcursesTargets"
+  )
+
+install(EXPORT "NotcursesTargets"
+  NAMESPACE "notcurses::"
+  DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/Notcurses"
+  FILE "NotcursesConfig.cmake"
+)
+
+install(FILES
+  "${CMAKE_CURRENT_BINARY_DIR}/Notcurses++ConfigVersion.cmake"
+  DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/Notcurses++"
+  )
+
+install(TARGETS notcurses++
+  EXPORT "Notcurses++Targets"
+  )
+
+install(EXPORT "Notcurses++Targets"
+  NAMESPACE "notcurses++::"
+  DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/Notcurses++"
+  FILE "Notcurses++Config.cmake"
+  )
+
 install(FILES
   ${CMAKE_CURRENT_BINARY_DIR}/notcurses.pc
   DESTINATION ${PKGCONFIG_DIR}

doc/man/man3/notcurses_cell.3.md

@@ -56,9 +56,9 @@ typedef struct cell {
 
 **unsigned cell_styles(const cell* ***c***);**
 
-**void cell_styles_on(cell* ***c***, unsigned ***stylebits***);**
+**void cell_on_styles(cell* ***c***, unsigned ***stylebits***);**
 
-**void cell_styles_off(cell* ***c***, unsigned ***stylebits***);**
+**void cell_off_styles(cell* ***c***, unsigned ***stylebits***);**
 
 **void cell_set_fg_default(cell* ***c***);**
 
@@ -74,7 +74,7 @@ typedef struct cell {
 
 **char* cell_strdup(const struct ncplane* ***n***, const cell* ***c***);**
 
-**int cell_load_simple(struct ncplane* ***n***, cell* ***c***, char ***ch***);**
+**int cell_load_char(struct ncplane* ***n***, cell* ***c***, char ***ch***);**
 
 **char* cell_extract(const struct ncplane* ***n***, const cell* ***c***, uint16_t* ***stylemask***, uint64_t* ***channels***);**
 

include/ncpp/Plane.hh

@@ -60,6 +60,20 @@ namespace ncpp
 			plane = create_plane (*n, rows, cols, yoff, xoff, opaque);
 		}
 
+		explicit Plane (Plane *n, ncplane_options const& nopts, NotCurses *ncinst = nullptr)
+			: Plane (static_cast<const Plane*>(n), nopts, ncinst)
+		{}
+
+		explicit Plane (const Plane *n, ncplane_options const& nopts, NotCurses *ncinst = nullptr)
+			: Root (ncinst)
+		{
+			if (n == nullptr) {
+				throw invalid_argument ("'n' must be a valid pointer");
+			}
+
+			plane = create_plane (*n, nopts);
+		}
+
 		explicit Plane (const Plane &n, int rows, int cols, int yoff, int xoff, void *opaque = nullptr)
 			: Root (nullptr)
 		{
@@ -69,7 +83,7 @@ namespace ncpp
 		explicit Plane (int rows, int cols, int yoff, int xoff, void *opaque = nullptr, NotCurses *ncinst = nullptr)
 			: Root (ncinst)
 		{
-			struct ncplane_options nopts = {
+			ncplane_options nopts = {
 				.y = yoff,
 				.x = xoff,
 				.rows = rows,
@@ -102,6 +116,16 @@ namespace ncpp
 			plane = create_plane (const_cast<Plane&>(n), rows, cols, yoff, align, opaque);
 		}
 
+		explicit Plane (Plane &n, ncplane_options const& nopts, NotCurses *ncinst = nullptr)
+			: Plane (static_cast<Plane const&>(n), nopts, ncinst)
+		{}
+
+		explicit Plane (Plane const& n, ncplane_options const& nopts, NotCurses *ncinst = nullptr)
+			: Root (ncinst)
+		{
+			plane = create_plane (n, nopts);
+		}
+
 		explicit Plane (Plane *n, int rows, int cols, int yoff, NCAlign align, void *opaque = nullptr)
 			: Root (nullptr)
 		{
@@ -1130,6 +1154,16 @@ namespace ncpp
 			return error_guard (ncplane_rotate_ccw (plane), -1);
 		}
 
+		char* strdup (Cell const& cell) const noexcept
+		{
+			return cell_strdup (plane, cell);
+		}
+
+		char* extract (Cell const& cell, uint16_t *stylemask = nullptr, uint64_t *channels = nullptr)
+		{
+			return cell_extract (plane, cell, stylemask, channels);
+		}
+
 		const char* get_extended_gcluster (Cell &cell) const noexcept
 		{
 			return cell_extended_gcluster (plane, cell);
@@ -1227,27 +1261,17 @@ namespace ncpp
 	private:
 		ncplane* create_plane (const Plane &n, int rows, int cols, int yoff, int xoff, void *opaque)
 		{
-			struct ncplane_options nopts = {
+			ncplane_options nopts = {
 				.y = yoff,
-			  .x = xoff,
+				.x = xoff,
 				.rows = rows,
 				.cols = cols,
 				.userptr = opaque,
 				.name = nullptr,
 				.resizecb = nullptr,
 				.flags = 0,
 			};
-			ncplane *ret = ncplane_create (
-				n.plane,
-				&nopts
-			);
-
-			if (ret == nullptr)
-				throw init_error ("Notcurses failed to create a new plane");
-
-			map_plane (plane, this);
-
-			return ret;
+			return create_plane (n, nopts);
 		}
 
 		ncplane* create_plane (Plane &n, int rows, int cols, int yoff, NCAlign align, void *opaque)
@@ -1262,16 +1286,21 @@ namespace ncpp
 				nullptr,
 				0,
 			};
+			return create_plane (n, nopts);
+		}
+
+		ncplane* create_plane (const Plane &n, ncplane_options const& nopts)
+		{
 			ncplane *ret = ncplane_create (
 				n.plane,
 				&nopts
 			);
 
-			if (ret == nullptr)
+			if (ret == nullptr) {
 				throw init_error ("Notcurses failed to create an aligned plane");
+			}
 
 			map_plane (plane, this);
-
 			return ret;
 		}