Initial multivfo implementation

Move ddc into receiver_base_cf
Move defines and modulation type to dedicated files
Implement config v4
Implement vfo selection by clickin the plotter widget
Implement stereo panning feature to improve listening experience
Implement locking vfos to a frequency and automatically delete locked
vfos when moved out of bandwidth
Add global lock/unlock context menu
Add global squelch auto/reset popup menu
Implement settings loading from a bookbark by right-clicking bookmark
tag on a plotter
Implement new vfo creation from a bookbark by middle-clicking bookmark
tag on a plotter
Add bookmarks context menu actions
1. To tune current demod to a frequency
2. To tune current demod to a frequency and load params from the
bookmark
3. To create a new demod with the bookmark params
Prevent new vfo creation over already active bookmark
Replace selected bookmark instead of adding new one at the same frequency
Update plotter overlay on bookmark delete
Update plotter overlay on bookmarks save
Save bookmarks on tag delete
Store all receiver parameters to a bookmark
Add a button to copy recording settings to all VFOs
Sort bookmarks by any column
Validate and correct filter params on input
Make Modulations class fully static
Allow to choose bookmarks table visible columns
Select a bookmark on exact freq match only to avoid a situation when
2 bookmarks have overlapping filter passbands and wrong bookmark with
wider filter passband is activated.
Automatically create demodulators when a bookmark, marked as 'auto' gets
visible on the panadapter.
Add a switch to enable/disable this function.

resources/icons.qrc

@@ -1,25 +1,28 @@
 <RCC>
-    <qresource prefix="/icons">
-        <file>icons/audio-card.svg</file>
-        <file>icons/bookmark-new.svg</file>
-        <file>icons/clear.svg</file>
-        <file>icons/clock.svg</file>
-        <file>icons/close.svg</file>
-        <file>icons/document.svg</file>
-        <file>icons/flash.svg</file>
-        <file>icons/folder.svg</file>
-        <file>icons/fullscreen.svg</file>
-        <file>icons/floppy.svg</file>
-        <file>icons/gqrx.svg</file>
-        <file>icons/help.svg</file>
-        <file>icons/info.svg</file>
-        <file>icons/play.svg</file>
-        <file>icons/power-off.svg</file>
-        <file>icons/record.svg</file>
-        <file>icons/refresh.svg</file>
-        <file>icons/settings.svg</file>
-        <file>icons/signal.svg</file>
-        <file>icons/tangeo-network-idle.svg</file>
-        <file>icons/terminal.svg</file>
-    </qresource>
+  <qresource prefix="/icons">
+    <file>icons/lock.svg</file>
+    <file>icons/remove.svg</file>
+    <file>icons/add.svg</file>
+    <file>icons/audio-card.svg</file>
+    <file>icons/bookmark-new.svg</file>
+    <file>icons/clear.svg</file>
+    <file>icons/clock.svg</file>
+    <file>icons/close.svg</file>
+    <file>icons/document.svg</file>
+    <file>icons/flash.svg</file>
+    <file>icons/folder.svg</file>
+    <file>icons/fullscreen.svg</file>
+    <file>icons/floppy.svg</file>
+    <file>icons/gqrx.svg</file>
+    <file>icons/help.svg</file>
+    <file>icons/info.svg</file>
+    <file>icons/play.svg</file>
+    <file>icons/power-off.svg</file>
+    <file>icons/record.svg</file>
+    <file>icons/refresh.svg</file>
+    <file>icons/settings.svg</file>
+    <file>icons/signal.svg</file>
+    <file>icons/tangeo-network-idle.svg</file>
+    <file>icons/terminal.svg</file>
+  </qresource>
 </RCC>