Corrected typo: ruke -> rule

Removed acronyms for "Perl" and "PERL" as Perl is not an acronym.

Internet Explorer 8 (and maybe others) seem to use different
capitalization in the ACCEPT_CHARSET header between "normal" requests
and AJAX requests. This causes a browser UID mismatch and thus an
unecessary reauthentication.

See http://learn.perl.org/faq/perlfaq1.html#Whats-the-difference-between-perl-and-Perl-

Made bin/striplangs.php executable

Made it easier to use, and consistent with the others bin/*php scripts

* added more selectors to allow different markup
* added border to make tabs more distinctive, especially in other templates

Proposed fix for #2541

added support for local style.ini files

#2541, alter section highlighting to insert a container into the DOM to hold the elements being highlighted & later remove it

note: we recommend to NOT use H1 elements in the sidebar for semantic
reasons