Make cataclysm compile in clang.

1. clang didn't like `point look_debug(point point=point(-256,-256));`
2. CXX is now set with ?= so if you have CXX=clang++ set in your environment, it won't be overriden.
3. Even though $(LD) was used to compile the cataclysm executable, it was passed arguments that only gcc and not ld accepts. Thus changed it from $(LD) to $(CXX)
WIP commit: Adding lua scripting capabilities.

- Initialized lua 5.1
- Wrapped game->add_msg for lua use
- Made Use_function's into a class that can use either lua or C++ functions
- Added a function for lua to register lua functions as iuse's
- Relies on a lua5.1/ include directory and a -llua5.1 link library being present
A wrapped item userdata is now passed on to lua iuse functions.

Only the id item member is wrapped so far.
Worked on a new lua binding generator, customized for cataclysm.