fallback name proposal

[ix0rai]

in order to facilitate QuiltMC/quilt-mappings#660, we're going to add a new method to NameProposalService: isFallback().

when true, the name proposer will be treated as a fallback proposer: the names will not count towards stats by default, and will be shown in the interface in a different colour (we've proposed blue and orange. drop your preference in the comments below). this will differentiate them from normal proposed names, which count as fully mapped entries for stats and are expected to be high-quality names like manual mappings.

this will be implemented for enigma 2.6!