Display custom values in work package table
Display total sums regardless of grouping option
Show sums for summable custom field columns in angular work packages table
Restructure json-rendering methods in work packages controller
Move work packages query form to partial
Move zoom slider and modal directives to component folder
Share work packages angular controller scope among query form and table
Merge branch 'feature/ui-component-table-widgets' into feature/angular-tables

Conflicts:
	app/views/work_packages/index.html.erb
Remove obsolete tree.
Freezes gon to ~> 4.0
Wire up toggler for all check boxes, toggle label appropriately (see #4123)
Updates pg gem.
Updates openproject-ui_components.
Merge commit '8a45a79' into feature/angular-tables

Conflicts:
	Gemfile.lock
	app/assets/javascripts/timelines.js
	app/assets/javascripts/timelines/TimelineLoader.js
	app/assets/javascripts/timelines/ui.js
	app/views/timelines/_timeline.html.erb
Wire up column in work packages query form
Move timeline view models to separate folder
Add query service and sketch its integration
Tidy watchers on groupings
Update work packages table data on switching the grouping
Let the query service manage the query to parameter conversion