Python OPI checker: add check for stray widgets

Following an issue in #1987 where we had a stray widget located at
```
-2147483647
2147483496
```
it would save debugging time later if the script checked OPIs for strange widget positions.

The `check_opi_format.py` script should be modified to check for these values. The following limits might be good starting points (we may need to make adjustments to these later):
```
-10 < x < 1000
-10 < y < 1000
```