libFirm can now be build as static and as dynamic library.
Two defines control it:
FIRM_BUILD must be set when libFirm is build.
FIRM_DLL must be set if libFirm is build as a dynamic library.

The old FIRM_DLL macro is now renamed to FIRM_API.

Additionally

- FIRM_API is added to the ADT headers, this is at least needed for edgfe.
- some more missing FIRM_API's added ...
- add a resource file to show libFirm's version under windows

[r27575]