[MAT-437] stub code for mldivide

This commit contains an initial shot at the implementation
and translation of the mldivide code. Considerable further
work and testing is required.
[MAT-437] Additional fixes to mldivide runner.

This commit contains additional work on the mldivide code and
the provision of a large number of unit tests. Main changes are
a swathe of bug fixes and the addition of strongly typed enums
for enum constant used in flow control.
[MAT-437] java tests added.

Contained within are a set of tests for the java wiring
to the mldivide() operation.
[MAT-437] Respond to PR comments.

Specifically this:
- Swaps cout for cerr
- Fixes 2 typos
- Moves that exclamation mark in README.md that has been glaring
at me for weeks.
Merge pull request #119 from OpenGamma/MAT-437-squash

Mat 437 - implement the mldivide operation