FIX: update outputlilypond submodule
FIX: update outputlilypond
FIX: add 'pieces' as default for WorkflowManager.load()
FIX: add 'pieces' as default for WorkflowManager.load()

(cherry picked from commit 00f29de6829221369233fb727f36c66ba2e49910)
FIX: cleanup docstrings
FIX: First Event in LilyPond Annotation Part Has Correct Offset

Closes #275
Fix: Refactor PartNotesIndexer._fill_space_between_offsets()

I think it looks much cleaner now, and it's more functional-paradigm.
update outputlilypond
WIP: PartNotesIndexer Can Include Part Names

Working toward #276, where annotation parts will have part names.
Merge local branch 'devel-1.2.0' into devel_2