Gas(GAS) Mainnet Upgrade

Neo-CLI v3.6.2 has been released. TestNet will be upgraded on Nov 21st. MainNet will be upgraded on Dec 4th.

Below is a list of improvements and optimizations included in this release:

• Add a new syscall "CurrentSigners" for getting current tx signers
• Add a new function in native StdLib contract name as "StrLen" for getting String length in smart contract.
• Set attribute fee for transactions with "conflict" attribute
• Add cancel command both in neo-cli and rpc for canceling transactions which haven't been on-chain yet.