+ added new USE_CAIRO config preprocessor def.
to differentiate from HAVE_CAIRO so that we can use the cairo lib
without forcing the full fltk lib to be linked against it.
In that case, cairo autolink context functionality which needs fltk lib
instrumentation is disabled.
+ added new --enable-cairoext, which correspond to previous --enable-cairo.
now, --enable-cairo only adds HAVE_CAIRO def. and keeps fltk lib
from referencing cairo.
In both cases (--enable-cairo & --enable-cairoext), a new fltk_cairo lib is
created. This lib, similarly to local versions of png,jpeg and zlib,
is not generated if cairo is not enabled.
+ added cairo to fltk-config : now new --use-cairo flag is available
+ modified all unix like makefiles to now generate minimum cairo deps and also
new libfltk_cairo lib.
+ added new cairo subdir to permit conditional fltk_cairo lib generation.
+ vc2005 project minimum update to compile without be broken, but still needs
to create a similar fltk_cairo independent lib. For now, it works as before
with a dedicated cairo env. similar to --enable-cairoext context in unix.
+ regression tested ok with cairo disabled on win32, mac osx, mingw.
git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@6462 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
