R112: Labels

Star labels added in R112: this is intended to be the last cosmetic fix before a general "refactoring" phase preparing for:

1. synergic mergers of similar structures according to C object orientation techniques – perusing similarities in struct declarations using a type tag and perhaps a virtual table implementation providing real dynamic method dispatch, such as generally invisible in C++
2. thereafter program loading and map setup.

I would have liked to sprinkle my star maps to Wikipedia sites (and Citizendium where there are no images at all), but it won't happen before program loading becomes beta and so mkmap becomes alpha.