Unify type system

[markus2330]

Currently, Elektra does not provide a single type system, but different plugins and bindings use different data types and different metadata for describing them (check/type vs. type).

Some places where currently types are used:

• src/plugins/type implements check/type via CORBA data types
• src/include/kdbtypes.h header files for CORBA data types
• high-level API uses CORBA data types
• internalnotification Internalnotification Plugin #828 uses CORBA data types
• src/plugins/yajl has JSON types stored in type (see yajl: Elektra's boolean not supported  #2571)
• src/bindings/jna uses Java parse* functions (not checking or storing metadata)
• ruby, python, lua also use their own types

obsolete

• code generators (src/tools/gen/) mostly use C/C++ types

Could you check/fix these places for consistency (value ranges, sign, ...) and document the type system at a single place? (So that the next plugins/bindings can simply implement what the document says)

[markus2330]

kdb get<int> does not throw if the type is actually boolean (0 or 1, check/type=boolean)

[markus2330]

Expected outcome is:

• documenting the interrelations of where metadata check/type is used
• fixing issues (e.g. that metadata type is currently not checked in C++ API)
• more unit tests of typed access

[markus2330]

To be fully compatible with CORBA types, we should:

• define mappings to our bindings
• add wchar
• add type safe CORBA Any type in C++ layer
• deprecate/remove empty and FSType

[markus2330]

@kodebach I assigned you as you were already working on it in #2399,

[markus2330]

@kodebach is this still open? src/plugins/yajl might be fixed already. Please reopen if something is missing.