Implement OLE-300

[bvbfan]

https://github.com/OmniLayer/Documentation/blob/master/OLEs/ole-300.adoc

Core part introduce a new cli parameter -omnisafeaddresses enabled by default in mainnet. It enforces using of bech32/m addresses with prefix o, in regtest it's useful for testing purpose. RPC methods takes and return addresses encoded in new format. omni_encodeaddress and omni_decodeaddress respectively encodes and decodes bech32 addresses, they are tool methods to help dealing with native addresses. On protocol side there is no changes, implementation is trying to prevent users to sends their money to custodial wallets thus tokens might be locked. So when user wants to receive omni layer tokens it should share its omni encoded address thus sender will use it in rpc or Qt wallet side.

Qt wallet is fully revamped, all dialogues are fully functional and could be tested in regtest by
LC_ALL=C ./qt/omnicore-qt -regtest -server -omnisafeaddresses=1 -fallbackfee=0.0002 -showdex=1
LC_ALL=C - locale Independent interface
-regtest -omnisafeaddresses=1 - on regtest it should explicitly enabled, it is only on mainnet
-showdex=1 - exchange page is disabled by default

Qt wallet fixes:

• Prevent random deadlocks
• Performance: Using wallet address instead of all ones in Balance/Send dialog
• Send dialog accepts only omni encoded addresses
• Receive dialog it can be select all omni layer token and create omni address and URI to be shared
• Payment server support URI bitcoin: as well as omni:
• MaidSafeCoin and Tether USD property ids 3 and 31 on mainnet will be shown as EMAID and USDT