Docs: Document file(GENERATE) CONDITION as optional.
Qt4Macros: Remove unneeded generate CONDITION.
Qt4Macros: Remove undefined varible use.

This may have been added in anticipation of processing COMPILE_OPTIONS,
but as moc does not accept them, there is no need for it.
Qt4Macros: Simplify some variable population.
Docs: Document existing target property debugging options.
Docs: Trim trailing whitespace in generated doc.
Docs: Generalize and de-duplicate VISIBILITY_PREFIX docs.
Docs: Document variables for default visibility values.
Export: Fix typo of LINK_INTERFACE_LIBRARIES.

Refer correctly to the old property, not the new one.
cmTarget: Remove duplicates when printing traces of tll signatures
cmTarget: Fix iface libraries and languages for static libraries.
Ninja: Make cmcldeps depfile output more consistent with 'ninja -t msvc'

Ninja relies on the generator to produce paths that match up with the
paths used in the build.ninja file, which are spelled with backslashes.
Therefore, cmcldeps should canonicalize depfile paths to use backslashes
and relativize paths to the build directory.
Ninja: Update BuildDepends test to verify cmcldeps depfiles.
Genex: Disallow LINKER_LANGUAGE only when used on a static library.

For shared libraries and executables, the linker_language is
indepenedent of the linked libraries.
FindGTK2: Use GTK_XXX_LIBRARY_DEBUG libraries in debug mode

If the GTK_XXX_LIBRARY_DEBUG library is available, it is now used when
linking in debug mode XXX.
A new set of variables GTK_XXX_LIBRARY_RELEASE is added and the
original GTK_XXX_LIBRARY uses the optimized/debug syntax.
FindGTK2: Append _LIBRARY to var name in _GTK2_FIND_LIBRARY

This avoids to get the base name using a regexp, in order to use
SelectLibraryConfigurations
FindGTK2: Append _INCLUDE_DIR to var name in _GTK2_FIND_INCLUDE_DIR

This is to keep _GTK2_FIND_INCLUDE_DIR and _GTK2_FIND_LIBRARY coherent
after previous commit
FindGTK2: Update local changelog
FindGTK2: Remove GTK2_SKIP_MARK_AS_ADVANCED option

Variables are now automatically marked as advanced by
SelectLibraryConfigurations
Merge topic 'FindGTK2Debug'

32cf738 FindGTK2: Remove GTK2_SKIP_MARK_AS_ADVANCED option
a874142 FindGTK2: Update local changelog
cd2d9c7 FindGTK2: Append _INCLUDE_DIR to var name in _GTK2_FIND_INCLUDE_DIR
732324f FindGTK2: Append _LIBRARY to var name in _GTK2_FIND_LIBRARY
03bd3d1 FindGTK2: Use GTK_XXX_LIBRARY_DEBUG libraries in debug mode