General stylistic cleanup.
Fix badly-spaced headings.
Add hook for FindMaterial.
Add in custom materials module.
Add blank file for custom materials replacements.
Add in module docs.
Change to pre-hook.
Fix commands not working.
Make sure to set the hook int when initializing the object.
Merge branch 'feature/custom-materials' into develop
Remove IsEnabled public function.
Fix commands not working.
Update README.
Bump version.
Update changelog version.
Merge branch 'release/0.21.0' into develop