* Make some minor translation fixes
* Remove crowdin file and add import function for crowdin zip file
* Rename fallback project lang file to en_GB
* Update all i18n files from crowdin exports
* Fix tests
* Update docs
* Fix bug in early error reporting in main init
* Update docstrings and optimise code in GuiMain
* Update docstrings and optimise code in Config
* Update docstrings and optimise code in common module
* Update docstrings and optimise code in main project classes
* Update the OptionState class
* Update the spell checker class
* Update the file converter classes and extend tests
* Update the about, merge, split and item editor classes and extend tests
* Update item editor test
* Update about dialog tests
* Some minor test cleanup
* Fix typo and add clarification in contributing guide
* Update instructions and readmes
* Cleanup in base files
* Cleanup in core files
* Cleanup in gui files
* Cleanup in dialog files
* Cleanup in tools files
* Cleanup in test files