Hashtag highlighting support. Fixes #12
Implement timed task in task model
Implement timed task in task builder
Reflect the change to UpdateTask
Modify @lowjoel visitor
Add DEFAULT_START_TIME
Fix the regression caused in test
Modify @lowjoel tests
Reflect the change in adding task/subtasks/dependencies
Implement serialization of start time
Lint fix
Use templated getOrDefault
Merge pull request #337 from angathorion/hashtags

Hashtag highlighting support.
Merge pull request #341 from evansb/subtask-api

Implement StartTime for timed tasks
Implement setting tasks with a high priority using /edit 0!
Implement /edit 0 by deadline.
Removed unused member variable committedTransactions
Put parameters to one line each if all do not fit in one line
Remove TODOs that are not going to be done
Update documentation