[BUGFIX] Automatically remove BOM from files before concatenation

Resolves: #72648
Releases: master, 7.6
Change-Id: I12d97a4bda70879c039d8b05390cc5e37fbeef51
Reviewed-on: https://review.typo3.org/45842


Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Reviewed-by: Wolfgang Klinger <wolfgang@wazum.com>
Reviewed-by: Martin Kutschker <martin.kutschker@ymail.com>
Tested-by: Martin Kutschker <martin.kutschker@ymail.com>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>