[BUGFIX] Excludefieds must exclude admin only tables

The field "allowed excludefields" should not show
fields of tables which are restricted to admins,
either because of the flag adminOnly =1 or
rootLevel = 1

Change-Id: Ie5a9c445275077984400017adc84dc0557d9c639
Resolves: #34460
Releases: 4.8,4.7,4.6,4.5
Reviewed-on: https://review.typo3.org/12853
Reviewed-by: Steffen Ritter
Tested-by: Steffen Ritter
Reviewed-by: Benjamin Mack
Tested-by: Benjamin Mack
[BUGFIX] BE user switch impossible when in adminOnly mode

Enables the switching of BE users when the BE is in adminOnly mode.

Change-Id: I059333da5453687222f24858b739c87f65b5109e
Fixes: #32686
Releases: 4.7, 4.6, 4.5
Reviewed-on: https://review.typo3.org/13011
Reviewed-by: Steffen Ritter
Tested-by: Steffen Ritter
Reviewed-by: Benjamin Mack
Tested-by: Benjamin Mack
[BUGFIX] t3lib_iconWorks must check if array exists before using it

A few places in t3lib_iconWorks use variables as arrays without
checking if they are actually arrays. This leads to warnings in
the syslog.

Change-Id: I5a7823c7d604a2960272fe7577075ed2309658bd
Fixes: #24248
Releases: 6.0, 4.7, 4.6, 4.5
Reviewed-on: https://review.typo3.org/12799
Reviewed-by: Marcus Schwemer
Reviewed-by: Wouter Wolters
Reviewed-by: Steffen Ritter
Tested-by: Steffen Ritter
Reviewed-by: Benjamin Mack
Tested-by: Benjamin Mack