Distribution 1.2.0

CHANGES:

Features

• Add keyword completion

• Add go to declaration functionality to jump to a value's specification in a
  .mli file (#294)

Fixes

• #245: correctly use mutexes on OpenBSD (#264)

• #268: Do not use vendored libraries when building the lsp package (#260)

• #271: Clear diagnostics when files are closed

• Disable non-prefix completion. There's no reliably way to trigger it and it
  can be slow.