Gene Modification Tokens (GMTs)

Define what Genetic Modification Tokens (GMTs) are, and what they can be used for (gene mods, unaltering, changing stable name). Discuss where to get GMTs (voucher exchange, buy upgrades, Candy/Sea Ponies). The bulk of the information about GMTs should be located here, with links directing here from other pages where GMTs are mentioned. Remember to link to other articles/subsections as needed.