Ensure asset links are a set
Simpler atomic write

Cache writes are already in a tmp dir, we don't need to write to
/tmp first. Just uses the current tmp dir. Then we don't need to
worry about permission changes either.
Avoid reparsing uri before merging new params
Merge more of the processed and static pipeline
Prefer explicit extensions when passed to resolve
Cleanup error message when no longer under path
Track unique asset uris with digest of entire object

Fixes caching issues with asset oid changes between load path
and other require changes.
Diff ids for diff envs

Fixes CI
Add find_all_linked_assets
Improve support for asset-path with query and fragment
Update dir fixture list
Deprecate Asset mtime
Merge branch 'master' into 4.x

Conflicts:
	lib/sprockets/asset.rb
	test/test_asset.rb
Drop Asset#mtime
Remove support for regexp matchers in manifest
Remove support for environment logical path iteration