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
functionEval does infinite evaluation of a function

functionEval 1 0.5 (Variable 'x') 'x' = map Value [1,1.5..]