Reorganize some packages and classes
Starting develop feats
Written Feat class, it should work.
Improved MersenneTwister, ended up with D20Character (? first version),
some minor improvements.
StringCompiler, in utils, lets me use the StrBuilder by
apache-commons-lang3 with a format string, same as String.format(String,
Object... args).
Localization implementation complete for current needs.