again, merged the common files into this repo since the common files are
only used here, no sense to make separate repo. may make a subrepo
later. also, finished writing the loading library method. FML rewrites
the classloader to load mods, so ordinary libraries won't be loaded. I
make a workaround that add the path to FML's classloader, so that it
could load it too. (nothing to change in FML, don't worry!)