Improve terminal behavior in various ways

[rondlh]

Improve terminal behavior in various ways

Requirements

Any touchscreen

Description

This PR improves the terminal in various ways:

1. The TFT firmware has a foreground and a background loop. The foreground loop handles the graphical aspects, while the background loop handles the key time critical processes in the background like serial data receiving and sending. When active, the terminal screen blocks the background loop because it needs the foreground loop to draw the incoming data on screen before it can proceed, this can cause data loss. This PR solves this issue.
2. The terminal seemingly deletes data at random (not really at random, but for the user it's not transparent). For long responses the terminal sometimes just gives the last lines of the response because it just deleted the data. The PR solves this issue.
3. You can now jump from the first page to the last page of the terminal history and the other way around.
4. Some color is added to the terminal keyboard to help the user to find the most common commands
5. The terminal history is now 5 levels deep (was 3) and survives a restart of the terminal screen.