The launcher stores the installed game version in its cache, which leads to several bugs:
- Updating to a different version and immediately closing and restarting the launcher makes it think it's on the new version.
 - The launcher is not aware of Steam game updates
 - The launcher cannot read the version of different game installs
 - The launcher does not know the installed game version if the user clears its cache
 
This absolutely must be fixed prior to the next launcher update.
Edge-cases:
- version.txt malformed
 - version.txt missing
 - fresh install (no version.txt, no StarMade.jar)