[FEATURE] Add option removePageCss to remove styles set in _CSS_PAGE_STYLE

Add the option »removePageCss«, equivalent to »removeDefaultCss«.
This option prevents the output of specific page CSS generated
by extensions like css_styled_content.
Create according entry for t3editor.

Resolves: #37818
Releases: 6.1
Change-Id: Ie1d68bd593b6895ea1fe5328b707f7ba9463ab8c
Reviewed-on: https://review.typo3.org/17708
Reviewed-by: Philipp Gampe
Tested-by: Philipp Gampe
Reviewed-by: Dan Untenzu
Tested-by: Dan Untenzu
Reviewed-by: Matthias Nitsch
Reviewed-by: Christoph Dörfel
Tested-by: Christoph Dörfel
Reviewed-by: Alessandro Bellafronte
Tested-by: Alessandro Bellafronte
Reviewed-by: Mattias Nilsson
Tested-by: Mattias Nilsson
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer
[BUGFIX] Numeric check for upper/lower bound of flexform-values

The range-check in Flexforms uses the same code as for normal
tables. Normally an integer field would be of type integer.
But in Flexforms the value is a string as is the value in DS.

Change-Id: I3512a961780a4bef91e04f61b8b9547f43f28f3e
Fixes: #15771
Releases: 4.5, 4.6, 4.7, 6.0, 6.1
Reviewed-on: https://review.typo3.org/9022
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer