Write concept for command messages and parsing
ignore studies dir
Add settings file for version and display of input keys.
Make background image configurable in settings.

Refactor less command. Integrate blink into less command.
Fix bug at backspace in shell. Refactor shell and history.

Rename Command to InputLine.
When a character was deleted in the input line, it was trimmed.
This caused two characters to be deleted when the last character
was after as space.