Release v1.6.0 on 2021-11-16.

1. ef4c597 vty/command: restrict the use of '.', '!', and '@' as flags by Vadim Yanitskiy · 3 years, 9 months ago
2. f94355d vty: check for reserved flags in application specific attributes by Vadim Yanitskiy · 3 years, 9 months ago
3. 024e195 vty: check for duplicate flags in application specific attributes by Vadim Yanitskiy · 3 years, 9 months ago
4. 68c2e73 tests: do not ignore stderr of vty_test, also match it by Vadim Yanitskiy · 3 years, 9 months ago