Merging of FTW and fiboa maps

[cholmes]

As we evolve towards FTW being the overall project we should merge the fiboa and ftw maps. This is dependent on #27 as we need to be clear on what this data is called. #10 should also likely be done in the same step, and the FTW map should enable users to see FTW benchmark data, FTW output data, other fiboa-formatted ML output (like UK fields), and all 'source' data - the bulk of the fiboa conversions of government data.

It should be easy to turn on / off each, and to visually tell them apart.

This should also likely be dependent on getting a single PM tiles for all fiboa source data.