Modular Maps

[blinkdog]

In upstream, the .dmm maps for output, ruins, shuttles, etc live in the directory _maps.

This base path is hardcoded in many places around the codebase, including the .dm source files, the data in the .json files in the _maps/configs directory, and tools under tools.

This PR changes this to a define MAPROOT. When the STARFLY_MAPS module is enabled, we use build tooling to supply modular maps in _maps2eb (_maps 2: Electric Boogaloo).

This uses a composition algorithm:

• First, we copy the upstream maps from _maps to _maps2eb
• Next, we recursively copy modular_starfly/**/_maps to _maps2eb (i.e.: our modules overwrite upstream maps)
• Finally, anything defined in STARFLY_MAPS is deleted from _maps2eb, which gives us the ability to remove upstream things that we don't want to replace.

In general, we'll leave _maps alone; it'll be the destination of upstream changes. We'll do our modifications within our modular_starfly modules.

Note: This PR is like #37 but I think this one actually works?

[blinkdog]

Okay, tested it Docker, and tested it locally on Windows.
Should be ready for prime-time, or at least day time.