We now parse out library names in order to compare them by group, path
and classifier instead of comparing the whole string.
Fixes #530 and #533

... with a caveat that it may break in future due to Quilt's broken
metadata

The meaning of `mapper.setSerializationInclusion` changed with the
Jackson upgrade, which meant that empty collections were being fully
stripped from the output. Fix by changing the strategy to NON_ABSENT,
which only strips nulls and "absent" values like Optional.absent

Removes a bunch of hardcoded workarounds :)

Also improved library handling some more

- Game/jvm arguments are now passed one-at-a-time, never grouped
- Added support for legacy version manifests by adding in the missing
arguments
- Correctly pull arguments from old manifests
- Some slightly hacky handling for old library stanzas
- Short-circuit if library URL has empty path to prevent accidentally
downloading HTML pages as jars
- Add launcherShortname prop, passed to --versionType

- Fix game arguments being missing from version manifest due to new format
- Update Runner to use more substitutions & support new argument model
- Move loader/installer libraries to their own section to avoid runtime conflicts
- Implement some basic feature matching for arguments

oh lord okay
- Update to new launchermeta endpoint for version manifests
- Fix library handling (libraries now seem to give us the URL most of the time)
- Write entire new system for handling the forge installer process
- Fix asset handling, mostly (still TODO is remove all traces of assetSource, it's given to us by launchermeta now)

This converts the project into a multi-module Gradle build.

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