refactored analyzecells, calctexture, dist, findcells, sortcells, and updatemap and integrated them back into one vol2bird library. Also, I moved the JNI counterpart of these methods to a new c-file 'libvol2birdjni.c' in order to not clutter Adriaan's C-code with JNI stuff. I also developed unit tests for the beforementioned methods. Still a lot of them fail due to errors, see issues #31, #32, #33, #34, #36, #37, #38, #39 on GitHub.