Added more code to cpu package

- In this: addition of cycle.py module stub
From now all project is in English language
Doxygen config
Setter for InstructionWord whole value
Few changes to 'asm' module
Improving doxygen config
Preparing terrain to develop the run of cpu
Bugfixes and migration to unittest platform

Doctests are useful but fragile. So I started the migration to unittest
from cycle module (one of the most importants).
Rename class: MicroStep => Stage

To improve meaning
Introduce class Step and changes to tests
DummyStep class
Step as a abstract class
Migrated assembler doctests to unittest
Defined abstract class Word

For be inherited by InstructionWord and DataWord
Improving unit test for Cycle
Reestructuration of Registers class
Renamed class: ExecutionCycle => CPUCycle
Changes to simplify CPUCycle interface
Convenience to access CPU registers by name
Bugfix at Registers class