LibNetBlock 1.7 released!

Significant portability updates. LibNetBlock now compiles on FreeBSD and macOS (as provided by Travis CI): https://app.travis-ci.com/github/bogdro/libnetblock.
Intercepting new functions and improvements in the old.
Improvements in banning.
Code quality improvements, including fixes recommended by Codacy.
Improvements in the build system.
Significant improvements in the documentation.
New unit tests.
Other small changes.