Same same, but different. (See previous commit for details.)

o Human-readable format of authentication method in overview
o Refine behaviour of enable / apply on main IPsec page
o Dedup leftsubnet/rightsubnet for meshed IKEv2
o More elegant interface and service plugging
o Tunnel isolation mode for IKEv2 (unmashed)
o Cleanup pass over backend code
o Allow Camellia for IKEv2
o Allow %any in phase 1
o Allow EAP-MSCHAPV2

Since the changes are splattered over several commits already
taken apart by other cherry-picks, just sync the files that
have not had their changes moved to stable/16.7 yet.

o Adapt to cipher output changes in OpenVPN 2.1.12
o Improve plugin probing for virtual interface
o Added missing IPv6 Tunnel Network for CSC

While here, remove the RAM disk mention, we can cope with this now.

(cherry picked from commit f85f3566)
(cherry picked from commit 02f9143e)
(cherry picked from commit 47988b58)

(cherry picked from commit 5ad7adc6)

(cherry picked from commit ffbb29e4)

Since we weaved the latter into the former, we can now get rid of
the transition code.  The behaviour doesn't change.

(cherry picked from commit 927f4e0e)
(cherry picked from commit 0b119652)

(cherry picked from commit 17b3374c)

(cherry picked from commit 6882250b)

(cherry picked from commit f88210b4)

* translation fixes (for example submit button)
* remove some not operators
* make short echo tags look more like a template

(cherry picked from commit d1e9265f)

(cherry picked from commit 7b59e10c)

The old script had a lot of unused code in it, either stuff that couldn't be configured from OPNsense or dead code.

(cherry picked from commit 9ba2b2f6)

(cherry picked from commit 0db74eff)

(cherry picked from commit bc2765ea)
(cherry picked from commit ac8eba7d)
(cherry picked from commit 87011deb)
(cherry picked from commit 5c6a2ef8)
(cherry picked from commit c782d9e8)
(cherry picked from commit 5497ae4e)
(cherry picked from commit 51aec445)
(cherry picked from commit 75e7e0e4)
(cherry picked from commit 2c25e3e3)
(cherry picked from commit dcd0e068)

(cherry picked from commit 15374ba7)

(cherry picked from commit c3daf44a)

(cherry picked from commit 9a117cd0)

(cherry picked from commit e6f5a191)

Reported by: Simon Brunet

(cherry picked from commit 5a21a07a)

(cherry picked from commit 9503d722)
(cherry picked from commit 69e28f84)
(cherry picked from commit 0cd0c895)
(cherry picked from commit 1334374b)
(cherry picked from commit d27cdb43)
(cherry picked from commit 2f5468ae)

(cherry picked from commit 1ccf6b45)

(cherry picked from commit d3d583ab)

Suggested by: @fabianfrz

(cherry picked from commit b218ce7d)

(cherry picked from commit a85a46b8)
(cherry picked from commit d7319957)

Suggested by: SimonB

(cherry picked from commit c6d2cca0)

There is no need to visually overload the field descriptions with
stop chars like a slash, the help is sufficient in explaining that
multiple networks can be used and the chances are high that most
will only ever use one network here.

(cherry picked from commit 1611955b)

Suggested by: SimonB via Pootle

(cherry picked from commit db356ac9)

(cherry picked from commit a94af0da)

Suggested by: @Antonio-Prado

(cherry picked from commit 7f9fcfb2)

(cherry picked from commit b56bcf83)

(cherry picked from commit ca1270a8)

(crashreport) PHP Warning:  in_array() expects parameter 2 to be array, null given in /usr/local/www/vpn_openvpn_csc.php on line 406

(cherry picked from commit d26cbd66)

(crashreport) PHP Warning:  in_array() expects parameter 2 to be array, null given in /usr/local/www/services_unbound.php on line 176

(cherry picked from commit 801d7ca0)

(packet capture) limit the maximum number of output lines, prevent "PHP Fatal error:  Allowed memory size of ..."

collected from crashreport

(cherry picked from commit aab13817)

(crashreport) PHP Warning:  Illegal string offset 'rule' in /usr/local/www/diag_logs_filter.php on line 277

(cherry picked from commit 64f3742f)
(cherry picked from commit 8f243538)

Revert "(ids) style fix", https://github.com/opnsense/core/commit/aaa0ddafe1179cebc68146bdc3c30b8b90c564b8 can cause "Allowed memory size of ... bytes exhausted", better to set a sane default max here.

This reverts commit aaa0ddaf.

(cherry picked from commit ed4c923c)
(cherry picked from commit f4e6e6f4)

(cherry picked from commit 4461ea23)

(cherry picked from commit cc18336d)
(cherry picked from commit cdf05735)

(cherry picked from commit 0be295ac)