`lexer.cpp.track.preprocessor` lexer properties affects which styles
are used, and we don't set those, so no filetype inheriting C styles
should set it to 1.

Similarly, some properties like `styling.within.preprocessor` are
mostly general settings rather than selecting syntax details, so they
should probably match in all filetypes for consistency.

So, inherit the C lexer_properties everywhere C styles are used, and
only override specific properties in the inheriting filetype.

C and C++ have Doxygen keywords from:
    http://www.stack.nl/~dimitri/doxygen/commands.html

Vala and Genie have Doxygen keywords and Valadoc keywords from:
    http://valadoc.org/#!wiki=markup

git-svn-id: https://geany.svn.sourceforge.net/svnroot/geany/trunk@5699 ea778897-0a13-0410-b9d1-a72fbfd435f5

git-svn-id: https://geany.svn.sourceforge.net/svnroot/geany/trunk@5698 ea778897-0a13-0410-b9d1-a72fbfd435f5

This provides separated single-line and multiline comment support.

git-svn-id: https://geany.svn.sourceforge.net/svnroot/geany/trunk@5609 ea778897-0a13-0410-b9d1-a72fbfd435f5

git-svn-id: https://geany.svn.sourceforge.net/svnroot/geany/trunk@5384 ea778897-0a13-0410-b9d1-a72fbfd435f5

git-svn-id: https://geany.svn.sourceforge.net/svnroot/geany/trunk@5344 ea778897-0a13-0410-b9d1-a72fbfd435f5

git-svn-id: https://geany.svn.sourceforge.net/svnroot/geany/trunk@4479 ea778897-0a13-0410-b9d1-a72fbfd435f5