[fltncurz] Floating cursor

When editing multi-line text on a touchscreen display, the cursor should float where the user touched his or her finger, not jump left to the rightmost character on that line.  The user can then use arrow keys to finely move the cursor to the desired final location.

We might want to visually distinguish between actual trailing space and floatable empty space.  And while we're at it, hard returns and line-break soft returns.

This might even be useful for regular computers, as I dislike fine positioning with the mouse.