Add command to select text using page up/down keys
Add text selection using page up/down keys to the React-based editor
Implement select page up/down in Editor
Add spec for Editor::selectPageUp/Down
:memo: Correct spec description
Merge pull request #2692 from atom/ks-select-page-up-down

Select page up/down
Prepare 0.107
:memo: Correct broken references
Batch all editor updates together automatically via process.nextTick
Default EditorComponent to updating synchronously in specs

This commit adds a static property, EditorComponent.performSyncUpdates,
which can be used to control the update behavior of all editor
components. In addition, an instance property called performSyncUpdates
be assigned to control the update behavior of a specific instance.
Emit events *after* update to prevent requesting update during an update

When updating synchronously in specs, we can't get away with requesting
an update before the previous update is completed. If we emit events
before the update, we have the potential for one of those events to
cause this to happen. Moving them to after is more correct anyway.
Only forceUpdate of EditorComponent on nextTick if it's mounted
Update markdown-preview to fix specs
Render highlights on their own layer to avoid GPU artifacts

Previously, when the last highlight div was removed from the lines
layer, chunks of the lines would sometimes disappear. Since we've
discovered that giving the lines an opaque background doesn't help with
subpixel anti-aliasing anyway, I've found that rendering highlights on
their own layer behind the lines and making the lines layer transparent
avoids the arficacts.
Merge pull request #2681 from atom/ns-react-batch-updates

Batch all editor updates together automatically via process.nextTick
Don't render an opaque background behind line numbers

It doesn't help subpixel anti-aliasing like I thought, so screw it.
Add a dedicated underlayer to avoid GPU artifacts on wrap guide etc

Trying to make the .highlights layer double as the .underlayer was
causing GPU artifacts on the wrap guide when the last highlight was
removed. This puts it in its own layer to avoid that.
Autoscroll to selections in model layer when added

Fixes #2698
Merge pull request #2702 from atom/ns-react-autoscroll-to-added-selections

Autoscroll to selections in model layer when added
Merge pull request #2699 from atom/ns-react-fix-artifacts

Render highlights on their own layer to avoid GPU artifacts