* Makefile: change location of FORMS library.
* posixmodule.c: turn #if 0 into #ifdef MSDOS (stuff in unistd.h or not)
* Almost all .h files: added CPP magic to avoid duplicate inclusions and
to support inclusion from C++.
Added $(SYSDEF) to its build rule in Makefile.
* cgensupport.[ch], modsupport.[ch]: removed some old stuff. Also
changed files that still used it... And made several things static
that weren't but should have been... And other minor cleanups...
* listobject.[ch]: add external interfaces {set,get}listslice
* socketmodule.c: fix bugs in new send() argument parsing.
* sunaudiodevmodule.c: added flush() and close().
* Fixcprt.py: added [-y file] option, do only files younger than file.
* modsupport.[ch]: added vmkvalue().
* intobject.c: use mkvalue().
* stringobject.c: added "formatstring"; renamed string* to string_*;
ceval.c: call formatstring for string % value.
* longobject.c: close memory leak in divmod.
* parsetok.c: set result node to NULL when returning an error.
