Moved around files in rt/ to mirror the directory structure used in android's libcore. The org.robovm.rt package is now in rt/robovm while the android classes are in rt/libcore.
Added the Android external/bouncycastle module to rt/. (#28)
Will now use rt/target/robovm-rt-<version>.jar instead of rt/target/classes if ROBOVM_DEV_ROOT has been set since otherwise we won't get the relocated bouncycastle classes.
Mangler.mangleString(String) in the compiler now uses Strings.stringToModifiedUtf8(String) to convert the string to be mangled to bytes instead of converting to UTF-8 using String.getBytes(). Strings.stringToModifiedUtf8(String) does not care if a character is invalid. (#30)