reworked MNCC codebase
This is Harald's reworked MNCC base, slowly heading towards integration
into master. The key changes are:
* provide much more structure to the data in gsm_mncc
* encode_* and decode_* functions now take a structure rather than tons
of individual arguments (whose order nobody can remember)
* make sure we don't have copies of the same code everywhere by introducing
mncc_set_cause() and mncc_release_ind()
* save horizontal screen space if possible
* make sure we break lines > 80 characters
15 files changed