edge: Add header type property to GprsCodingScheme

The header type depends on the coding scheme, for GPRS there is a
single data header type per direction, for EGPRS there are 3 per
direction. In addition, control block header types are used with CS-1
only, so there is one of the per direction altogether for GRPS and
EGPRS.

This commit adds the header type enum and two methods headerTypeData
and headerTypeControl.

Sponsored-by: On-Waves ehf
3 files changed