**BUG**
Concise problem statement:
Can't ever re-show a pin that has been hidden.
Steps to reproduce bug:
1. Set "Show" to "No" on the schematic view of a custom part. Save it.
2. Set "Show" to "Yes". Save it.
3. Add that part to a schematic, it doesn't show that pin anymore.
4. Re-load the edit tag for the part, "Show" is back to "No".
