Add Fl_Window::wait_for_expose() and test program (STR #3124).

Also modified .gitignore, svn-properties, Makefile and CMake-Files.

Todo: test/twowin.cxx and test/windowfocus.cxx need to be added to ide files
(MS VC++ and Xcode).


git-svn-id: http://seriss.com/public/fltk/fltk/branches/branch-1.3@10339 ea41ed52-d2ee-0310-a9c1-e6b18d33e121