(cherry picked from commit 867ecd70)

(cherry picked from commit 5e07d411)

(cherry picked from commit 88803cca)

(cherry picked from commit 51531ca0)

(cherry picked from commit 8decc7a3)

(cherry picked from commit 00769b55)

All the work done by the amazing @adschellevis !

(user manager) add datepicker + small html style issues, closes https://github.com/opnsense/core/issues/552

(cherry picked from commit 956a13f6)

(cherry picked from commit 387cce08)

(cherry picked from commit e15693e9)

(cherry picked from commit 3d012d96)

(cherry picked from commit 78b5def3)

(cherry picked from commit 2325fc61)

(cherry picked from commit 86431768)

(cherry picked from commit 71655d55)

This reverts commit d335ebf7.  This will
have to stay on -devel for a while longer.

(cherry picked from commit ed5c0dde)

(cherry picked from commit 06817d43)

(cherry picked from commit 62870e38)

(cherry picked from commit 731a9566)
(cherry picked from commit d25e1259)
(cherry picked from commit 5e97c86d)
(cherry picked from commit 8ff7c87f)
(cherry picked from commit 65882381)
(cherry picked from commit 8c9be5ca)
(cherry picked from commit 4958ea7b)
(cherry picked from commit 98485c39)
(cherry picked from commit 5a10f56a)
(cherry picked from commit 5d80d462)
(cherry picked from commit fd3ac67c)
(cherry picked from commit 9ce4fc1d)
(cherry picked from commit af4ce2d0)
(cherry picked from commit ed8c5a4f)
(cherry picked from commit 9f12e7f7)
(cherry picked from commit 8be72857)
(cherry picked from commit 07799412)
(cherry picked from commit c09b9299)

(cherry picked from commit ceafaf0a)

(cherry picked from commit 55d37aff)

(cherry picked from commit 53f6dace)

(cherry picked from commit 2aca9405)

(cherry picked from commit 809625fd)

(cherry picked from commit f286da8e)

(hasync) add dns resolver to sync, service restart not included, probably needs a seperate page at some point. closes https://github.com/opnsense/core/issues/923

(cherry picked from commit 53c1001b)

(cherry picked from commit c46d5ad0)

(cherry picked from commit 2533e110)
(cherry picked from commit b17d74fa)

(cherry picked from commit a445548a)

(cherry picked from commit 67a3a7e8)

(cherry picked from commit fd4c8acf)

(cherry picked from commit 4021045e)

(cherry picked from commit a404c216)

(cherry picked from commit 6e5fbbc9)

(cherry picked from commit 160c1245)

Taken from: http://www.iana.org/assignments/icmp-parameters/icmp-parameters.xhtml

(cherry picked from commit aa21adfe)

(cherry picked from commit 9ff3fcc7)

(cherry picked from commit 10d4cbfd)