Fixed multiple warnings and errors when compiling on Linux and added full support for OSX.

Fixed multiple warnings and errors when compiling on Linux and added full support for OSX.

I also did a few changes to the readme file as well as update the version number to 3.0.

Later I'll write wiki entries on how to compile on Linux.

Credits to:
@Diath for Helping me fix an error when compiling for Linux.
@djseban for the Mac OSX fixes.
@mathiasbynens for the diff [here](https://github.com/hjnilsson/rme/issues/64).