Support for function pointers and references

[Ondrej Oprala]

Hi everyone,
I recently pushed my proposed changes to the ondrej/fnptrs branch if 
anyone wants to try/comment/review them. Any and all comments are welcome.

There is one known issue/non-issue and that is that some type-id's are 
wasted in the output of abidw, meaning a function-type is assigned a 
type-id but is not emitted in the end. The coherence of id='X' and 
type-id='X' across the abixml is of course maintained.

Thanks,
  Ondrej