Support for more display drivers

[noah1510]

At the moment only MAX7219 and MAX7221 are expected to work correctly.
I the future all of the code in LedController_low_level.hpp should get refactored.

• add a generic display_driver class which has information about the specific command, byte order, etc.
• allow the controller_configuration to have an Instance of that class as option
• use that config option to send commands in LedController_low_level.hpp

I don't know when this will be done but it might be a good issue if you want to get started contributing to open source projects.

[noah1510]

469fae4 moved all of the opcodes and chartable into a separate class. This reduces the amount of #define statements and removes one public variable. It is also the groundwork for this issue.