We should reuse .ui files from Namecoin-Qt

[JeremyRand]

We could save a lot on duplicated effort by reusing the .ui XML form files from Namecoin-Qt. Unfortunately, the current .ui files make various assumptions that make them unsuitable for including verbatim in Electrum-NMC, and maintaining a fork of Namecoin-Qt's .ui files seems to be of dubious utility.

Incomplete list of assumptions that need to be fixed in Namecoin-Qt:

• [ ] managepagenames.ui tableView needs to be replaceable by UNOList in Electrum-NMC.
• [ ] configurenamedialog.ui transferToLayout needs to be replaceable by the analogous UI from Electrum.
• [ ] Get the name UI actually merged to Namecoin Core master branch so that this is actually relevant in the first place.

[JeremyRand]

I'd like to at least switch to .ui form files for the 4.0.0 milestone, even if we need to maintain a few small patches compared to Namecoin Core initially.