Add parser and node for Brevity file line.
Bunch of changes, supporting exporting and file processing.
Move dynamic changes from sequence to expression grammar.
Add Itemization class to hold notes, dynamic changes, tempo changes, etc. instead of using Part class.
Add failure reason to LineParseError message.
Found bug in FileProcessor#make_score (not tested of course).
Attempt to fix bug with labeled sequence composition.
Allow single-note modifications, without screwing up sequence parsing. Fix some bugs in tests.
Forgot to add these files...
Fix bug relating to start dynamic/tempo offset.
Fix bug when parsing empty line
Add support for comments.
Support tempo changes.
Add optional beat duration to tempo.
Add support for parsing commands, preparing to modify Brevity syntax.
Transition to command-based syntax.
Add commands for expr, part, and starttempo.
Integrate commands into ScoreMaker.
Start updating documentation to cover commands and expressions.