Bug: zero video phone demand unless mobile has been sold

[Akuukis]

There's no video phone demand, unless mobile phone is first researched and sold at least once.

Repro & Actual behavior
1. Make sure noone else (bots) have researched Mobile Phone
2. Research, produce & retail Video Phone
3. Notice that Video Phones don't sell
4. Research Mobile Phone
5. Notice that Video Phones still don't sell
6. Produce Mobile Phone
7. Notice that Video Phones still don't sell
8. Sell Mobile Phone
9. Notice that Video Phones start to sell as well

Expected behavior:
- Video Phones sells regardless whenever Mobile Phone has ever been sold
- and/or lock Video Phone research behind Mobile Phone

Notes
- Version 8.0.08
- save file attached (snapshot at repro step 3)

[David]

We will fix this in the upcoming version 8.1.00.