Implement the grammar for setting dependents and subtasks.
Issue an edit query for setting a task's dependency and subtasks.
Fix lints.
Merge pull request #298 from lowjoel/add-subtasks-and-dependendies-editing

Add subtasks and dependendies editing
Minor fixes to documentations
Merge pull request #305 from digawp/doc-fix

Minor fixes to documentations
Refactoring.