We Must Go Deeper: Submapping (NOT YET WRITTEN)

TODO: Write-up that explains the concept of sub-mapping. Should showcase both Flag and Definition submapping and the simple way of reading them like "<[a.b]>". Should explain how MapTags are generated and how you can read the root key to get a MapTag, and then use .get[] on it if wanted. Should give some general notes about MapTags. Should compare using . based submapping to using MapTag explicitly for the same tasks. Should describe both quality-of-code improvements and potential performance differences. Should also showcase definemap. Should showcase building a definition or flag initially from a direct MapTag like <map[a=b]> and then modifying keys within. Should show that removing the root also removes the nodes inside. Should show that replacing the root effectively clears any other keys inside as both a potential mistake and a useful tool when intended.