Power: Multiple changes.

Renamed interfaces and classes.
Cleaned up implementation.
Added examples and tests.
Added documentation.
Environment: Added documentation and cleaned up.
Ieee80211Mac: Added proper node shutdown and crash support.
Test: Followed rename libinet -> libINET.
build: fixed issue where the whole inet was rebuilt on each compile (from theIDE)
build: fixed issue while building with the LWIP feature enabled
doc: fix for documentation build error.
copyright header adjustments
WHATSNEW and ChangeLogs update /1

- added missing ChangeLogs
- added 'inet-3.x' note to all ChangeLogs
"changes in the inet-3.x branch:"
Changelogs update /2
WHATSNEW: Added geometry, environment, power and physical layer models.
doc: moved changelogs under the src/inet tree