Modified Arithmetic.hs

Added some versions of opNLog that are more convenient and/or optimized
(for example, if you give a nullvalue parameter it can now be way more
stack friendly)
Modified RoadSystems.hs

Added comments, speed improvements
Modified Arithmetic.hs

Changed algorithm for determinants to match the one I posted on
wikibooks, fixed a bunch of other things
Modified BinTrees.hs

Added a function that gets the height of the tree
Modified Euler.hs, ListOps.hs

Added a bunch of solutions to Euler,
Fixed a few other things in ListOps
Modified MergeSorts.hs

Added the sort function from Data.List