Overhaul - generic types for scalars and basis keys

[inakleinbottle]

This is a tracking issue for adding the new scalar and basis key types.

(I had written out a long description of the changes, but I caught a bad key combination and closed the tab making all that unrecoverable. I'm not typing it out again.)

TODO

Rational Coefficients

• Add rational type

Polynomial rational coefficients

• Indeterminate class
• Polynomial class
• Polynomial Type
• A better means of constructing besides by string
• Bracket access to individual coefficients

Lie basis

• Lie word (may or may not be a real Lie basis element, the basis must determine this)
• Lie word type

Tensor basis

• tensor word
• tensor word type