Port existing Star Rod mods to starpkg file structure

[bates64]

$ starpkg new my-mod --port path/to/existing/star-rod-mod

The reasons for this are twofold:

• It allows anyone currently using Star Rod (e.g. the Master Quest team) to quickly start developing their mod with starpkg.
• It means we can intuitively support patching ontop of ROM dumps (i.e. those made with SR's 'Copy assets to mod' feature) with a special package dependency that just references part of a local dump of Paper Mario. For the moment, we can just export the entirety of the dump as pm64, but I would like to eventually add support for being selective about which enemies/items/sprites/etc are brought in - e.g. a package that uses pm64_goomba but not pm64_koopa_troopa.

The path provided to --port will need to parse mod.cfg in order to figure out the version of Star Rod that was being used (BuildVersion, or assume 0.1.13 otherwise) and read the file structure accordingly.