Asset Validation Override in Coin Extensions

[CaveSpectre11]

Several coins, likely starting with PIVX, have errors in the the address validation regular expression; notably the leading character check wasn't deducted from the count of the following characters; so the address validation will incorrectly accept 35 character addresses.

The invalid address checks in Test all contain an invalid first character; therefore the only part of the regex tested is that leading character; so while other test addresses were meant to cover length and other invalid characters; none of the test parsing passed the first character test.

[CaveSpectre11]

After submitting, I was going to assign myself the issue, but I think I need to have something done so I can do that.

[CaveSpectre11]

Pushed in #2023

[CaveSpectre11]

Cleaned up my fork and branch. New clean push #2025