It is now possible to write `pkt[TCP].flags.S = True`.

This makes it possible to write `if pkt[TCP].flags.S: [...]`.

[coverage] More unit tests for scapy/*.py files

[DOCS] Installation + Links fixed (Windows)

Make SourceIPField() .i2m() and i2h() methods consistent

[coverage] VRRP, L2TP, HSRP, RIP, & Radius tests

[coverage] main.py tests

[Windows] Fix quotes under windows

Improvement of the GTPv1 support.

A new test that triggers the bug (with ARPSourceMACField) has been added.

[coverage]  AS resolvers tests

- Removed useless depedencies (Windows)
- Added more links through the doc's parts
- Removed broken links
- Markes scapy v1 as deprecated