Implemented dependency highlighting.
Lints
Added constants.
Highlight dependencies, test fixes
Refactoring of task columns
Fixed lints.
Use the expect operator where possible since it is more efficient.

Conflicts:
	You-NLP/query_parser.cpp
Use more expects when using explicit commands.

Conflicts:
	You-NLP/query_parser.cpp
Test for #287 by demonstrating that the show command can be used without a space delimiter.
Implement the grammar for setting dependents and subtasks.
Merge pull request #289 from angathorion/highlight-dependencies

Highlight dependencies
Merge pull request #293 from lowjoel/use-expect-where-possible

Use the expect operator where possible since it is more efficient.
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
Break after each switch case
Merge pull request #309 from digawp/gui-minor-fix

Minor fix to GUI
Implement building an add query with subtasks.