Support for autotools based build

This is the first version of an autotools based build system, the existing cmake files are still intact so you can actually choose if you would like to build with autotools or with cmake. The configure script is usually not checked in and has to be generated with: autoreconf -i

I also made sure that the original cmake files are available in the "make dist" tarball.

Personally, I find autotools a lot user friendlier i.e. ./configure --help=short and so on, imho much nicer as the -Dwhatever stuff + the inability to pass additional CFLAGS/LDFLAGS from command line since they are ignored by cmake. But everyone has their own preference, so why not have both?

I had to rename the core directory due to a known problem, basically while running various checks the configure script may generate core files which it then deletes, if a directory named "core" exists then an error message will be printed each time the script attempts to remove the core file. This is a known autoconf limitation and there is unfortunately no way around it, except for not using a directory named "core" in the $(top_srcdir)

I did not have the chance to test if the autoconf setup will work with mingw on windows, I did add some if's in the makefiles and a mingw environment detection in configure, but since I do not have windows anywhere I can not test it, so I'd appreciate if anyone could give it a try.

The next step would be to compile the core part as a shared library which I already did on another branch, but I'd like to work out this request first and see if it gets accepted before I put in more features for the build.