RGBDS-structs v1.2.1

Added:

• Named instantiations!
• dstructs to define an array of structs (in RAM only, doesn't make sense in ROM)
• More error checking to avoid confusing/unhelpful RGBDS errors
• Warning about readability

Modified:

• Minor code readability improvements

Fixed:

• Named instantiations were broken in v2.0.0, hence why that version was skipped