Make function/procedure arguments work.

Update lots of smaller things:
- Make Dump() methods callable from debugger by removing ostream arg.
- Allow "no else" on if-statements.
- Don't produce Phi node for if-statements.
- Make implement AND/OR keywords.
- Fix some copy'n'paste typos in builtin functions.
- Check for NULL returns in more places to avoid crashing.
- Add `-lm` to final link stage to allow cos, exp, etc.
- Separate out builtin functions from general functions.
Update README
Change namedobject handling and remove variables.h