Consolidate test library
This issue should cover following topics:
- Consolidation of CANtestlib.vhd. Add missing comments, format the code properly (4 spaces indent), remove unnecessary functions
- Add new set of functions which can be used in "feature test". Due to many changes in the register map, most of the feature tests are broken. If feature tests will be repaired, and register map changes again, there will be need for further reparations! This is undesirable. There is an idea to create set of low level functions which access the registers (sth. like HAL) and feature tests will only use these functions to execute tests. If register map changes, only test library must be updated, and test code and test logic can remain unchanged!