Simple and Direct Update

Rough overview in video format:
https://odysee.com/@Schoki:1/hawps_0-8:6

Added a SDL backend to terminal client, making it the desktop client.
Added ability to remove statusbar elements via compile time config.
Added missing mouse wheel actions to help text.
Added test code, which already caught some bugs the moment it came about.
Fixed chemical reactions not happening in world corners.
Fixed thermo tool speed when used via keyboard, which should now be on par with mouse use.
Improve flag handling error messages.
Improved code.