BridJ: added a very useful BRIDJ_DEBUG_POINTER_RELEASES=1 / -Dbridj.debug.pointer.releases=true mode (also enabled when BRIDJ_DEBUG_POINTERS=1)
JavaCL: fix horrible random native crash (double release, found with new -Dbridj.debug.pointer.releases=true). Could be the root cause of #420 and/or #405.