v2.21.0

v2.21.0
Using file: CHANGELOG.md
Adoption by Linuxgurugamer
Added InstallChecker and AssemblyVerison.tt
Fix bug where a null entry in the renderers would throw an exception
Thanks to github user @Scialytic for this:
PR originally submitted to original repo:
QoL improvements for parts with a large number of subtypes
Thanks to github user @StonesmileGit for this:
PR originally submitted to original repo:
Handle ModuleFuelTanks nodes