* Makefile: use cp -r to install the library

* ceval.c: use #ifdef COMPAT_HACKS instead of #if 0
* Makefile: fix to make clmodule.c compile;
  make config.o dependent on libpython.a (so date is always correct)
* timemodule.c: now sleep() also takes a float argument.
* posixmodule.c: added nice().