Changes:
- Native GoBGP support for BGP v4 Unicast
- gRPC based API support
- Command line client (fastnetmon_api_client) with options to block, unblock and list blocked hosts
- Enabled flow counters by default due to popularity
- CentOS 8 / RHEL 8 support
- Ubuntu 20.04 support
- Added CircleCI support and automatic night builds for binary packages
- Extracted build system from install script into fastnetmon_build.pl
- Binary packages (include GoBGP) for all leading Linux distributions
- Added support for artificial sampling rate in AF_PACKET mode
- Added option to control fanout mode in AF_PACKET
- Implemented dynamic feature detection for atomics and AF_PACKET
- Migration to C++ 11 capable compilers for all platform (CentOS 6 uses custom gcc 9.x compiler)