1.1.3.70

https://github.com/hyle-team/zano/releases/tag/1.1.3.70

[+] core: added new DB engine: MDBX (experimental, use --db-engine=mdbx), more info on MDBX benefits: https://github.com/leo-yuriev/libmdbx#improvements-over-lmdb
[+] wallet: safety improved when saving data: free space and possible write errors are taken into account
[*] wallet: fixed incorrect wallet’s balance on certain stages of contract processing
[*] core: very old pre-hardfork nodes are now filtered out by P2P subsystem to avoid meaningless traffic
[*] GUI: minor fixes and improvements
[*] API: fixed resync market issue
[*] core: fixed rare multithread synchronization issue
[*] P2P: fixed a rare case of double connections between nodes
[*] P2P: fixed a rare case of invalid handshake handling
[*] core: Linux binaries are being built in Ubuntu 16.04 environment now (was 18.10)