add TriangularIndexedVector
add indexing function for AArrayVector and descendents
slicing for AArrayVector
misc edits
make band operations final
refactor Vector.equals
optimised add override for strided vectors
Merge pull request #52 from prasant94/develop

Add householder implementation to QR decomposition.
Merge branch 'develop' of https://github.com/mikera/vectorz.git into develop
shrink over-large test case
Changed order of multiplication to use sparseness.
Merge pull request #54 from moygit/develop

Changed order of multiplication to use sparseness.
pull from develop