* 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 "access *: ...", made access work for class methods.
* Introduced subclass check: make sure that when calling
ClassName.methodname(instance, ...), the instance is an instance of
ClassName or of a subclass thereof (this might break some old code!)
yet). The class is now passed to eval_code and stored in the current
frame. It is also stored in instance method objects. An "unbound"
instance method is now returned when a function is retrieved through
"classname.funcname", which when called passes the class to eval_code.
