SNClient

Changes:

- implement external scripts
- add support for client certificates
- add hashed passwords
- improve internal checks

Changes:

- implement filter and thresholds
- packaging
  - add windows service mode
- add command alias support
- add log rotation
- add optional automatic updates

Changes:

- add packaging
  - windows
  - rpm
  - deb
- add nrpe support
- add check_nsc_web rest api support
- add basic checks
- add basic prometheus metrics