Move files in preperation for creating a package

Partial commit to deal with renaming and then editing
Move mlabwrap.py in to __init__.py of new package
Use new MatlabInstance object to get single Matlab

Use as a sort of singleton instance so that we can make sure
we only ever spin up one Matlab instance. Better than calling
an init function on the MlabWrap class. Still allows you to
create as many instances as you want using the MlabWrap class
Update the documentation to reflect changes
Eat error when garbage collecting MlabWrap instance
Fix a load of warnings during cpp compilation

Mostly to do with unused variables and passing string literals.
Unfortunately the default Python API has some weird tendancies
to expect string literals but have them cast as char*, which means
I end up creating const char* and then casting them back to
char* to squash the errors...
Build properly and bump to version 1.2
Merge branch 'master' of https://github.com/patricksnape/mlabwrap