Commands are registered in WorldLoaded event handlers, and IngameChatLogic takes all registered commands and provides tab completion. However IngameChatLogic is also created during WorldLoaded via LoadWidgetAtGameStart. No initialization order is enforced between commands and LoadWidgetAtGameStart, so they can appear in any order.
If a command gets registered before LoadWidgetAtGameStart runs, then it will get tab completion. If it gets registered after then no tab completion is available, even though the command can still be used and appears when using '/help'.
To fix this, we allow the tab completion to check for available commands lazily, meaning it will check for available commands every time the tab key is pressed. This means it will always have the full list of commands available regardless of the initialization order.
Error messages are displayed using the following methods:
* **zenity** parses pango markup and replaces escaped characters
* **kdialog** replaces (some) escaped characters
* **gtk-dialog.py** replaces `\n`
* **printf** interprets format strings and replaces escaped characters
* **echo** just displays the text
The error messages themself contain escaped characters and paths from variables.
This PR unifies the behavior by:
* Use **printf** to format error messages and replace escaped characters
* Setting `--no-markup` for **zenity** to disable pango markup and escaped characters
* Remove `\n` replacement from **gtk-dialog.py**.
* Use plain **echo** instead of **printf**
Use **xargs** to pass results of **find** instead of word splitting. Word splitting fails when filenames contain white spaces (or if no files are found).
To prepare them for documentation generation.
Also added descriptions to SpriteSequence implementations and their properties.
Also made a few code style fixes.
