Clean up of mym

My attempt at a self-contained package for mym. It should build easily on all platforms without additional external dependencies:
 * MySQL connector for Windows, Linux and Mac is included
 * zlib is included for Windows and Linux to avoid conflicts with outdated library version on older MATLAB versions
 * Shared libraries are modified to load their dependencies from the local directory they live in. Further minimizes version conflicts
 * The compiled versions for all platforms are maintained on the [distribution branch](https://github.com/datajoint/mym/tree/distribution)