* Wrote missing constructor functions for ringlike structures.
* Merged LeftDistributivity and RightDistributivity into a new trait called 'Distributivity'.
* Added the values 'LeftAnnihilating' and 'RightAnnihilating' to the trait 'Annihilating' to accurately model the constraints on near rings.
* Removed the No[X]-values from all traits that modeled the assertion that a trait was NOT present. That feature was useless.
* Changed .gitignore.
* Changed makeStructureTypeSynonym in Templates.hs: now one can specify which traits are present AND with which value.
Removed the ability to name structures via 'tags'. While there is a use-case for such a feature, it is just obtrusive most of the time and the user can add it himself if he wishes to do so.
Removed tags throughout the package.

* Added Relation module as a wrapper around Relation.Internal.
* Corrected documentation, explained Internal modules in cabal file.
Fixed tag problems in Relation.
Merge branch 'master' of https://github.com/jtapolczai/algebra