Important bugfix in range syntax
fromMb is called fromJust in Data.Maybe
Some tests for introducing units
Simplifies base units to newton, pascal
Enabled possibility to convert numbers to prefices
Symmath.Eval now uses Monad Transformers (Reader -> Error -> Identity)
Some more simplify for sums...
Deriving units
Watt, Joule added
Better common factor matching
Fix parser bugs in funName and mathConst
Rudimental units parser

Limitations:
* "1_m" doesn't parse, you've got to write "1*_m"
* SI prefixes don't work
Make parser fail if input isn't consumed completely
Add prefix support to unit parser
Major improvements

Simplify is now able to simplify terms like x - (x - y) to y. Some other
things, too.
Merge branch 'pu/funtable' into next
Merge branch 'pu/parse' into next
Merge branch 'pu/eval' into next

Conflicts:
	Symmath/Eval.hs
Merge branch 'pu/simplify' into next

Conflicts:
	Symmath/Simplify.hs
	Symmath/Util.hs