Motion: DifferentialDriveController: make it possible to reenable motors
UI: GUI: Add license headers to all GUI files.
UI: GUI: Fix include guards.
UI: GUI: Adapt to namespace convention.
UI: GUI: No indentation inside namespace.
UI: GUI: Add/remove newlines to make the code more Allman style.
UI: GUI: Reformat all documentation.
Add proper doxygen grouping with `gui`.
UI: GUI: Refactor unused variables warnings.
Merge branch 'feature/gui_cleanup' into develop
UI: GUI: Fix ColorPalette for clang compiler.
UI: GUI: Rename DEFAULT_COLORPALETTE ~> DefaultColorPalette.
UI: GUI: Copy default palette in Constructor.
UI: GUI: Default constructor for xpcc::gui::Color.
Merge branch 'feature/gui_cleanup' into develop
Fix box naming.
SPI: Add non-blocking coroutines to SimpleSpiMaster interface.
SPI: Add coroutine implementations for AVR.
Coroutine: Unittest: check if enum class values can be returned
Coroutine: make it possible to return values of all types that have a default constructor
AVR: Make index static within function.