0.5.0 release

Another year, another “minor” version. “Half-way to 1.0” feels strange to say, but it may be somewhat accurate. Most of the changes in the past few months have been internal, although I’ve also moved some of the logic out of specific games that I’ve written and into the engine proper (for example, pushable blocks). This has significantly streamlined the whole process, as I learned in the last week with my latest game jam submission, Rime or Reason.