The PD-classes files are now a part of the main Shattered Pixel Dungeon project as a gradle module, this repository is no longer being maintained. It remains here in order to show the history of changes between Shattered Pixel Dungeon v0.1.0 and v0.4.2.
You can find the latest version of this code (now a gradle module referred to as SPD-classes) here: https://github.com/00-Evan/shattered-pixel-dungeon/tree/master/SPD-classes