Begin to abstract settings

Also normalize some line endings.
Pass in settings provider to Settings

Rather than making it an interface everyone has to buy into, leaving it as
static class makes it simple to keep the existing logic for things like
command bindings. With the added ability to set the internal provider used
by the static class, we can now gain testability over settings without
reworking existing usage.
Kill MainForm
Normalize line endings
Merge settings-abstraction