Automate / unify build scripts for Unix/Windows

Use one script for each generic platform, Unix or Win32, to build Mpm. The script will use determine to use either qmake with mpm.pro or prepare generic makefile as default make.

The script will unify to use build/ as scratch area for object files and as final output.

First step is to just get this unification working with a release build. Later, add debug and release targets. The clean target will delete all scratch and compiled folders.

Once it all is working, backport to Master, so v1.5.0 release also benefits from a better generic, unified build process.