Added separate main program for the Mac: macmain.c

Added separate main program for the Mac: macmain.c
stdwinmodule.c: wsetfont can now return an error
Makefile: add CL_USE and CL_LIB*S; config.c: move CL part around
New things in imgfile; also in Makefile.
longobject.c: fix comparison of negative long ints...  [REAL BUG!]
marshal.c: add dumps() and loads() to read/write strings
timemodule.c: make sure there's always a floatsleep()
posixmodule.c: rationalize struct returned by times()
Makefile: add test target, disable imgfile by default
thread.c: Improved coexistance with dl module (sjoerd)
stdwinmodule.c: Change include stdwin.h if macintosh
rotormodule.c: added missing last argument to RTR_?_region calls
confic.c: merged with configmac.c, added 1993 to copyright message
fileobject.c: int compared to NULL in writestring(); change fopenRF ifdef
timemodule.c: simplify times() using mkvalue; include myselect.h
  earlier (for sequent).
posixmodule: for sequent, include unistd.h instead of explicit
  extern definitions and don't define rename()
Makefile: change misleading/wrong MD5 comments