Added info directory.
Classified tgi_imulround() as part of TGI API.
Added cc65_umul8x8r16() based on umul8x8r16.
Finetuned Git commit hash retrieval.

- Force usage of shell wrapper in order to allow to suppress potential message about git not found (thanks to Greg King).
- Do $(info GIT_SHA ...) only if there's something special - as done with the other $(info ...).
Fixed typo.
Merge remote-tracking branch 'upstream/master'
Make ld65 -L command line option position independent again.
Handle long versions of command line arguments correctly.