Introduce more colour definitions

[maks]

I'd like to propose introducing more colour definitions. ie entries in the ColorDefinition enum in View.h.

Initially I would like to add the following:

• CD_ERROR for showing error messages or conditions, eg. the colour for the batt gauge when critically low level.
• CD_WARN for showing warning messages or conditions
• CD_INFO for show informational messages or conditions

My plan for warn and info is to initially use them as the colours for the base and middle parts of the "VU led bar" meters and error for the clipping range once I start working on the mixer screen PR again, so initial defaults of green, yellow and red for these three new colours respectively.

[democloid]

Totally fine. Main thing to keep in mind is that there are a total of 16 colors available per the driver, so need to use wisely and think a bit ahead. That can be expanded of course, at the cost of memory.

[maks]

Thanks for that @democloid ! And thanks for the pointer to the limitation on 16 colours, I didnt realise that 👍🏻 I can't think of any more colours I would want to add for now, but for sure need to add these strategically.

I'll start on a PR for this shortly.