Fix #19 weird MScript issue on Windows
Return the original MScript when trying to overwrite, so that the variable isn't accidentally cleared.
Fixes #20
Merge branch 'cdev' of github.com:rsmenon/MATLink into mma-dev
CompileMEngine[] should not return anything.
Merge branch 'mma-dev' of https://github.com/rsmenon/MATLink into cdev