Introduced Iterators
Merge remote-tracking branch 'upstream/master'
Introduced Iterator
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
Performance optimizations
Removed Iterator
Removed iterator traits
Re-Added iterators with working covariance
Merge remote-tracking branch 'upstream/master'
Removed trailing spaces.
Merge pull request #14 from emiswelt/master

Added Iterator trait to DoubleModList, small changes regarding hash function