Updates and merges

A few things have happened:

• I have merged this extension and window_progress together.
• The DLL is now much smaller (see blog post).
• I added a GMS2.3 x64 version of the DLL.
• The extension is now free and open-source.
  Given that the two extensions made a total of $40 in 4 years, it doesn’t seem like making purpose-specific $1 extensions is much of a business plan.