Extends ctranspose() to Tridiagonal matrices
Extends transpose() and ctranspose() to Tridiagonal matrices
Elementary transformations of Tridiagonal matrices

Extends conj(), transpose() and ctranspose() to Tridiagonal matrices

Also adds very elementary tests of these functions
Fleshed out elementary +,-,x,\ operations on Tridiagonal and SymTridiagonal matrices

Where necessary (esp. in matrix multiply) the output type changes so that the output is still preserved gracefully. In particular where needed:
- SymTridiagonal is converted to Tridiagonal or dense
- Tridiagonal is converted to dense

Fixed apparent bug in copy(Symdiagonal)

Also some light cleanup of tridiag.jl
Merge pull request #2611 from jiahao/tridiag-simpleops

Elementary operations for Tridiagonal and SymTridiagonal matrices