[Minor] To the line of code stand out in the comments
[Fix/Refactor] Fixed incorrect order of handler executsions (in mod_CUsMgr and mod_filterCUs) when 'Esc' is pressed with filter search box having focus

- plus, some refactoring
- plus, binding `tab` key in mod_CUsMgr using mod_keyboardLib instead of addEventListener
Merge branch 'master' of https://github.com/MakeBetter/Units