Resolve a few TODOs.
Move TODOs to GH issues.
Return null for measurement if never received.

Comment was wrong, AIDL can return null.
Trigger location updates when we received speed, too.
Remove a resolved TODO - VI API is rewritten.
Move a TODO to an issue.
Remove resolved TODOs.
Move TODOs to GH issues.
Move a TODO to an existing GH issue:

https://github.com/openxc/openxc-message-format/issues/11
Add a few minor tests for VehicleManager.
Remove a few resolved TODOs, clarify the threading model for BT VI.
Move a TODO to a GH issue.
Check for required fields when deserializing binary diag response.
Clean up deserializing binary Command with a diagnostic request.
Standardize labels in Enabler status - no colon suffix.
Watch for changes in VI preferences to know when to show file icon.

Fixed #184.
Remove unused import.
Simplify logic for creating fragment for ViewPager.