No longer need this test file.

This works now.

Previously, if backwards was on and point was before the first number on
the line, the start position would be set to 0 (when it gets set to
`$previous_match_start`). This means the start position wouldn't get set
to the actual start position of the first number.

We want the actual start position of that number so we can move point
only if it's on or after the current number when changing between
negative and positive numbers.

Also, the `\G` pattern didn't work on some of the `sed` tests because it
matches a number at that position. Since the position wasn't one that
was followed by the number, the regex didn't match a number, and the
increment didn't happen. We can get rid of the special handling for
start position at 0 now.

In order to set up point moving only when point is on or after the start
position of the changed number, I want the second return value from
`incdec()` to always give me the correct start position.

Currently, it returns 0 as the start position when backwards is on and
point is before the first number. It should return the start position of
the first number.