Small clean-up to edas/tools.py
Small clean-up to edas/tools.py

- Removed some list() casts applied to iterators.
  This cast only forces a useless expansion. Is only useful when you need to
  modify the list.
- Changed hash_fields from dict to tuple. Smaller and faster.
- Eliminated a big (and potentialy dangerous) try/exception.
  Replaced by a simple if. Could shadow a real error.
- Added comment about missleading comment and potentialy dead code.

xesscorp/KiCost,hildogjr/KiCost,xesscorp/KiCost,hildogjr/KiCost,xesscorp/KiCost,hildogjr/KiCost