Outliner: Fix range select not activating

Outliner: Fix openclose behavior

Fixes click+drag on disclosure triangles not behaving as expected.
Now the dragged elements will be either closed or opened depending
on the state of the first clicked+dragged.

Also removed walk in and out for arrow left and right.

Outliner: Synced selection fixes

Fix outliner select on items linked between collections not
syncing.
Adds more control to from-outliner select syncing, to only sync
data within the current interaction mode.
Deselect all non-synced data on syncing to outliner.
Fix edit bone outliner syncing not tagging for updates

Outliner: Don't show duplicates in merge search

Outliner: Remove set parent popup

The popup did not allow operator reports with multi object
support.

Outliner: Move synced select toggle

Move below Sort Alphabetically and use a checkbox instead of
a button.

Outliner: fix contrast for selected and active highlights

Merge branch 'master' into temp-soc-2019-outliner-sync

Merge branch 'master' into temp-soc-2019-outliner-sync

Outliner: Add range extend select and modify keymap

Modifies selection keymap to be more conventional, with
shift click for range selection and ctrl click for extend
selection.

Outliner: Support box select on click+drag

Outliner: Use entire selection for parenting

Set and clear parents for all elements in the selection in the outliner.

This also rewrites the popup menu for setting parents to armatures,
curves, and lattices to support multiple objects, though it removes
the operator reports for failures in those cases.

Outliner: Fix scenes in scene display not starting open

Outliner: Fixes to show active and scroll page

Adjusts the scrolling of show active and scroll page operators
to use the `outliner_scroll_view` operator to ensure scrolling
does not leave the outliner bounds.

Also changes show active to expand subtrees containing all
instances of the active object, which may be linked to multiple
collections.

Outliner: set scene camera on camera data activate

Outliner: Draw sequencer and vertex group icons

Draw icons for sequencer and vertex groups. The sequence
types need updates because they all draw in various colors
and some sequence types do not have an icon.

Merge branch 'master' into temp-soc-2019-outliner-sync

Outliner: Use F2 to rename active outliner item

Previously with F2 mapped to the global rename active object
operator, it was not posible to use the conventional F2 to rename any
outliner element like collections or object data. This adds F2 to the
outliner keymap to call the outliner rename operator rather than the
popup rename object operator.

Outliner: walk navigation operator

Adds a keyboard walk navigation and selection operator to the
outliner. Up and down arrow keys walk up and down the list of
elements, and left and right walk in and out or open and close
elements if the elements are open or closed.

Also moves opencolose toggling to the openclose operator to
remove duplicate code.

Also allows click+drag for openclose of element subtrees.

The outliner tree building is tweaked slightly to set the proper
parents in scene display mode for walk select to function
correctly.

Outliner: invisible object filter

Adds an invisible object filter in the outliner to show hidden
objects. This is useful to quickly locate hidden items in a large outliner
tree and easily toggle visibilty back on. Invisible refers to an object
being hidden, or viewport visibility restricted.