Rename triple* -> quad* files
Remove quadfix
Rename triple entities were relevant
Simplify method name
Simplify godoc
Add basic support for mongo testing

This is not intended to be for general consumption at this stage; it
requires that the tester has a mongod instance running and because of
the time taken to load the db, $GOROOT/src/cmd/go/test.go must be
modified to allow for tests longer than 10 minutes. A future CL may
allow db probing and the use of an existing cayley test dataset.
Make hashOf a function
Merge pull request #148 from kortschak/renaming

Renaming triple-related entities to the quads they actually are (eg, TripleStore -> QuadStore)