Fixes #1441: Ctrl-c dropping a character when selecting from right to left in insert mode

[Chillee]

In insert mode, selecting from left to right results in one more character being selected, so our old workaround was to shift the end of the selection to the left if we're in insert mode.

So this is how the cursor selections look when we're in "".
In Normal mode dragging from left to right or right to left,
"|fooba|r"
In Insert mode dragging from left to right,
"|foobar|"
In Insert mode dragging from right to left,
"|fooba|r"

Thus, it works normally if we're selecting from right to left.

Also fixes #1355

[xconverge]

Thanks, since this was special cased already it LGTM