Update develop with enforced value fixes

[blondfrogs]

• Added Bip Logic for the new ENFORCE_VALUE BIP which will enforce reissue assets to have a value of 0 in the txout.nValue - 62c30f9, 905952c, 787d4c0, 9c8fbc0, 8141607, c455cfc, 185a052, 09578af
• Added new rpccall decodeblock - ae65a29
• Updated GUI version checking to use configure.ac variable - 8c1fb71, 627a6f0, 405e1ee

Code Added by developers:
@akshaynexus - 8c1fb71
@blondfrogs - 62c30f9, 905952c, 787d4c0, 9c8fbc0, 8141607, c455cfc, 185a052, 09578af, 627a6f0, 405e1ee, ae65a29, e889065

Closes #795

[spyder46n2]

Nice work, I liked running throught the code review via Zoom.

[TronBlack]

I'd feel more comfortable if these were
#define CONSTANTS

bool fCheckBlock = true;
bool fCheckDuplicates = true;