* Initial code check in for background images
* Cleaning up whitespace
* Whitespace cleanup
* Added/fixed comments
* Fixing tabs
* Reverting erroneous file add
* Removing custom enum for image stretching mode and using Windows::UI::Xaml::Media::Stretch instead.
* Removing now-superfluous static_cast when setting stretch mode.
* Updating code to use wstring_view (per #925)
* One last set of wstring -> wstring_view changes
* Split off brush-intialization function from TermControl::_BackgroundColorChanged and added code to prevent flicker on resetting acrylic or image backgrounds.
