Move keys that initiate select mode to the command factory
Add paste to insert mode
Prototype select mode from insert mode
Use list comprehension to simplify expression
Obey 'keymodel=startsel' (still needs eventing)
Add Shift+Left, Shift+Right in insert mode and add settings event
Fix Ctrl+G to switch between visual and select modes

- Change several places to check for both modes
- Record anchor point and caret start on entrace to select mode
Adapt insert mode unit test infrastructure for recent changes
Ensure OnEnter and ModeSwitched are called "in the new mode"
Normalize caret position on entry to normal mode
Use OfCommandResult instead of matching by hand
Fixes for line-wise motion in select mode

- Fix exclusive selection of empty lines
- Workaround for broken EditorOperations.MoveLineDown, e.g., by clearing selection first
Remove trailing whitespace
Refactor common code in OnEnter of visual and select modes
Add select mode from insert mode unit tests
Fix duplicate keys in insert mode command map
Merge branch 'fixes-1243-part-ii'