ktis: engine stop - comment re: naming conflict?
kpvs: fix naming and inconsistencies

- Removed some currently unnecessary KPVs:
  - Eng{EPR,Torque}{Above,To}FL100Max
  - EngTorqueAbove10000Ft{Max,Min}
- Change 500-0 to 500-20 for Eng{EPR,Torque} (like EngN1)
- Simplify derive() for EngGasTempDuringFlightMin
- Updated names to match naming convention.
- Unit test fixes:
  - Added a few missing test cases and stubs.
  - Removed some duplicate or obsolete test stubs.
  - Implemented some of the .can_operate() tests.
- Added units to the KPV definitions.
- General tidying up of relevant nodes and test cases.
  - Strip excess docstring placeholders.
Merge branch 'master' of github.com:FlightDataServices/FlightDataAnalyzer

Conflicts:
	analysis_engine/key_time_instances.py
fix and tidy up imports