[BUGFIX] Compressor resolves dots in filenames correctly

Method getFilenameFromMainDir() tries to resolve a given file path
to a path relative to the document root and takes care of file
existance.

Sometimes it is fed with a path like '../path/to/file' and then
prepends it with the document root to call an is_file() on it. The
constructed path is then '/path/to/doc/root/typo3/../path/to/file'. If
now 'root' is a symlink to some sub structure itself, is_file()
will fail, because it does not solve the '..' part correctly anymore.

Using resolveBackPath() on the path before feeding it to is_file()
transforms the path to '/path/to/doc/root/path/to/file'. So the dots
are resolved and is_file is happy.

Change-Id: I20b4f4bbea695aeb02e3d92469236bc63cd05d97
Resolves: #52926
Releases: 6.2, 6.1, 6.0, 4.7
Reviewed-on: https://review.typo3.org/24875
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters
[TASK] Add xlf to [SYS][textfile_ext]

Add the xlf file extension to the list of textfile extensions in the
default configuration.

Resolves: #53136
Releases: 6.2
Change-Id: I2ea509c8a027bb21d77a59313cce4dfa9495c280
Reviewed-on: https://review.typo3.org/25008
Reviewed-by: Philipp Gampe
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer
[BUGFIX] T3editor: Honour fileDenyPattern on saving included TS

fileDenyPattern is only checked on loading so far.
Needs to be added for saving as well taken into account, since
otherwise an arbitrary file (including .php) can be overwritten.

Change-Id: Ia7edc83c8954942fb848746abc0980a304a1a6df
Resolves: #53195
Releases: 6.2, 6.1, 6.0, 4.7, 4.5
Reviewed-on: https://review.typo3.org/25046
Reviewed-by: Francois Suter
Tested-by: Francois Suter
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer
[BUGFIX] No duplicate html encoding in file titles

This patch makes sure that UserFileInlineLabelService only parses the
title of a file through htmlspecialchars if this was not already done by
a BackendUtility method like getRecordTitle() or getRecordTitlePrep().

Titles that are cropped by getRecordTitlePrep() will be displayed
correctly in the Backend.

Resolves: #53200
Releases: 6.2
Change-Id: I960e599372aeecfb2e5e6469ac4d644c578cfabc