Integrated: Merge lworld

[Vicente Romero]

Merge lworld into universal-tvars

-------------

Commit messages:
 - additional changes
 - Merge branch 'lworld' into universal-tvars_merge_lworld_last
 - Merge lworld
 - Merge lworld
 - left-overs from last type system refactoring
 - Merge lworld
 - addressing several issues in the implementation of universal tvars
 - Merge lworld
 - Merge lworld
 - changing universal lint warning to unchecked warning
 - ... and 24 more: https://git.openjdk.org/valhalla/compare/6cd250ff...1dc5cbae

The merge commit only contains trivial merges, so no merge-specific webrevs have been generated.

Changes: https://git.openjdk.org/valhalla/pull/813/files
  Stats: 1608 lines in 33 files changed: 1493 ins; 28 del; 87 mod
  Patch: https://git.openjdk.org/valhalla/pull/813.diff
  Fetch: git fetch https://git.openjdk.org/valhalla pull/813/head:pull/813

PR: https://git.openjdk.org/valhalla/pull/813