Editor Feature: Key shortcuts for inserting new lines

[AndyHOvine]

This is a nice idea I saw in another editor which would be useful to have in TRSE:

1. Hold SHIFT and press ENTER to insert a new line below the current cursor position without moving everything to the right of the cursor down to the new line, IE: effectively it is like pressing END to go to the end of the line then pressing ENTER. Cursor is now on the new line.

2. Hold ALT + SHIFT and press ENTER. Same as above but the new line is inserted above the cursor. IE: like the user pressed HOME to go to the start of the line, then cursor UP then ENTER.