New PascalCoin Build 1.5.4

Source code at GitHub:
https://github.com/PascalCoin/PascalCoin

Download windows installer and Linux binaries at SourceForge:
https://sourceforge.net/projects/pascalcoin/files/

Upgrade is mandatory if using old versions (prior to 1.5)


### Build 1.5.4.0 - 2017-03-15

- Added Network Timestamp Adjustment (NAT) to calc valid timestamps
  - Minimum 4 active connections to calc median used for NAT, otherwise use local timestamp
  - Based on IP's (to prevent a malicious IP timejacking, each IP is only used once)
  - Removed IP's and recalculated after disconnecting (to prevent malicious node connecting/disconnecting for timejacking)
- New blocks will not be accepted if using future timestamp greater than NAT timestamp + 15 seconds (also, mantaining current protocol rule >= lastBlock.timestamp)
- Network protocol fixed to 5-5 (Nodes with version prior to 1.5 will not be allowed)
- Added protection for non included operations on a block, to prevent continuous sending. Only will resend operations once.
- Bug #27 fixed: Invalid timestamp on FPC (https://github.com/PascalCoin/PascalCoin/issues/27)
- JSON-RPC
  - Method "getconnections" added "timediff" to know timestamp diff of node
  - Method "payloaddecrypt" added "unenc_hexpayload" result value with HEXASTRING of unencrypted payload
- Fixed some "Random Memory access violation errors" bugs found caused by multithreading and disconnected nodes