Advanced DHCP Client Options & Config File Override

DHCP v4:
Protocol Timing
Send Options
Request Options
Require Options
Option Modifiers

DHCP v6:
Interface Statement
Identity Association Statement
Prefix Interface Statement
Authentication Statement
Keyinfo Statement

DHCP v4 & v6:
Config Override File
Add section tag to v6 documentation links.

Put v4 send, request, require & modifies in lease requirements and requests section.
No functional changes.
Config file formating:

FIX - Add new line after comment so first option statement is on uncommented line.
Prefix send host-name with tab.
allow defining dhcp static mappings using dhcp-client-identifier
add MSS clamping to setup wizard. Now that MTU and MSS are separate, the MTU description was wrong, and both need to be there.
not true you have to log in again since HTTP basic auth was deprecated.
Don't flip the IPv6 allow setting just because people are upgrading. Just upgrading versions shouldn't change this behavior. As much as most of us would like people to start deploying IPv6, the vast majority aren't going to be immediately post-upgrade, and changing this can change the firewall policy behavior by allowing v6 that previously wasn't allowed. Upgrades should never change the firewall behavior like that. At the time it was done, everyone using the 2.1 code base was using it for IPv6, so of course it tripped up quite a few people.
Provide full path to route binary
Provide full path to route binary
Remove unreferenced binaries. correct some formatting and also to make function clear to track correct the curly placement
Use trim rather than str_replace. Also no need to sleep anymore since dhcp will configure first the interface
Get interface from inet6 domain
Do not do the same tricks here that are done on get_real_interface but just call the function directly
Remove useless variable and also correct some style
Use family parameter for v6 to get correct interface
* Use when needed the family for get_real_interface
* During dhcp setup use -n for cp to avoid coping uselessly
Use file_put_contents for simplicity and readbility
Remove unused code and spurious alert
Remove referenced binary not used anymore
Add used binary