posixpath.py: added undocumented expanndvars() (expands $VAR in string).

posixmodule.c: waitpid() is separate

added gettext() method to TextEdit.py;
fixed string.atoi() to ignore leading zeros.

* socketmodule.c: get rid of makepair(); fix makesocketaddr to fix
  broken recvfrom()
* socketmodule: get rid of getStrarg()
* ceval.h: move eval_code() to new file eval.h, so compile.h is no
  longer needed.
* ceval.c: move thread comments to ceval.h; always make save/restore
  thread functions available (for dynloaded modules)
* cdmodule.c, listobject.c: don't include compile.h
* flmodule.c: include ceval.h
* import.c: include eval.h instead of ceval.h
* cgen.py: add forground(); noport(); winopen(""); to initgl().
* bltinmodule.c, socketmodule.c, fileobject.c, posixmodule.c,
  selectmodule.c:
  adapt to threads (add BGN/END SAVE macros)
* stdwinmodule.c: adapt to threads and use a special stdwin lock.
* pythonmain.c: don't include getpythonpath().
* pythonrun.c: use BGN/END SAVE instead of direct calls; also more
  BGN/END SAVE calls etc.
* thread.c: bigger stack size for sun; change exit() to _exit()
* threadmodule.c: use BGN/END SAVE macros where possible
* timemodule.c: adapt better to threads; use BGN/END SAVE; add
  longsleep internal function if BSD_TIME; cosmetics

Also, get rid of makepair() in favor of mkvalue().

* split pythonmain.c in two: most stuff goes to pythonrun.c, in the library.
* new optional built-in threadmodule.c, build upon Sjoerd's thread.{c,h}.
* new module from Sjoerd: mmmodule.c (dynamically loaded).
* new module from Sjoerd: sv (svgen.py, svmodule.c.proto).
* new files thread.{c,h} (from Sjoerd).
* new xxmodule.c (example only).
* myselect.h: bzero -> memset
* select.c: bzero -> memset; removed global variable

* select.c: bzero -> memset; removed global variable

Minor, minor changes to commands.py and sndhdr.py.

Got rid of old module 'localtime.py'.

>   added 'clobber' target

really was).

fileobject.c: report more moeaningful error for I/O on closed files;
user getargs() everywhere.

Added new module dbm (interface to ndbm).

interfaces to variants of select() system call, "myselect.h".  This includes
adding fileno() methods to files, sockets and stdwin.

arguments crashed in INCREF() calls which should be XINCREF() calls.

timemodule.c: fix for SEQUENT port (sys/select, struct timezone) by
Jaap Vermeulen

xxobject.c: include modsupport.h