TODO list:

Critical:
- finish float/double support. add function type convertion.
- section generation and GNUC __attributte__ handling.
- D option with '=' handling
- 0 is pointer - fix type compare
- To check: 'sizeof' may not work if too complex expression is given.
- fix 'char' and 'short' casts (only in function parameters and in
  assignment).

Not critical:

- interactive mode
- fix multiple compound literals inits in blocks (ISOC99 normative
  example - only relevant when using gotos! -> must add boolean
  variable to tell if compound literal was already initialized).
- fix L"\x1234" wide string case (need to store them as utf8 ?)
- fix preprocessor symbol redefinition
- better constant opt (&&, ||, ?:)
- add ELF executable and shared library output option (would be needed
  for completness!).
- add PowerPC code generator.
- add portable byte code generator and interpreter for other
  unsupported architectures.