Sparse Matrix Support

Sparse matrices can now be created with build.x

Bidirectional Unique

Merging

Merge branch 'master' of github.com:jaredlander/useful

Conflicts:
	README.Rmd
	README.md

ggplot2 mods

Explicitly calling functions from grid and scales rather than importing the entire packages.
The function subVector now returns the original text x if toSub is not supplied.