It is now possible to use #ifdef/#ifndef to exclude some part of the
file. The implementation uses a stack to track conditionals so it is
possible to use nested constructs.
A number of macros are pre-defined by WindowMaker for CPP in the
function 'MakeCPPArgs', they are now available in the internal
parser too. CPP also had some predefined macros, a subset of them
have been added.
The definition have been split in two parts:
- the macro that are dependant on WindowMaker parameters are
defined by WindowMaker (src/rootmenu.c)
- those that are independant, which can be defined by the parser
itself (WINGs/menuparser_macros.c)
This adds support for defining new macros, with or without parameters, which
when found afterwards in the text are replaced by their definition.
The complex analysis for arguments replacement is done at macro definition
time, so it is done only once and the macro expansion will be fast.
The macro-related functions have been placed in their own file because it is
quite a complex task and we do not want filesize to explode, it is always
better to keep things human-sized.
