Bug 25257: Preserve prolog on translated XML files

Bug 25257: Preserve prolog on translated XML files

This patch fix the missing xml prolog in translated
files, XML or TT.

Is fixed teaching C4::TTParse not to ignore <?..?> constructs,
then teaching xgettext.pl to ignore those strings. Net result is
that they are copied in the translated file.

To test:
1) Update & install your preferred language,
(cd misc/translator/; perl translate update xx-YY; perl translate install xx-YY )

2) Compare the first lines (head -2) of:
koha-tmpl/opac-tmpl/bootstrap/en/xslt/compact.xsl
koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-opensearch.tt
koha-tmpl/intranet-tmpl/prog/en/xslt/plainMARC.xsl
and
koha-tmpl/opac-tmpl/bootstrap/xx-YY/xslt/compact.xsl
koha-tmpl/opac-tmpl/bootstrap/xx-YY/modules/opac-opensearch.tt
koha-tmpl/intranet-tmpl/prog/xx-YY/xslt/plainMARC.xsl

Check the missing prolog

3) Install this patch, repeat 1 and 2, now the prolog is present
on translated files.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>