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

Replaced it by the old tpl_include_page() and made it more flexible by adding a boolean $propagate parameter.
(It's false by default for backwards compatibility reasons. Should it rather be true? That would probably be what most users want.)

This reverts commit ea62d531.

Update template footer with HTML5 icon (FS#2619)

This fixes the problem that $PARSER_MODES was sometimes unset by PHPUnit
between test functions that called p_get_parsermodes() as PHPUnit tried
to restore the global environment. I couldn't reproduce this when I
executed all tests but just when I executed a single plugin test.

This problem was reported in https://forum.dokuwiki.org/thread/8143.
Apart from warnings you could notice that when you have namespaces "foo"
and "f.o" and you open the sitemap for "foo" that "f.o" is opened, too.

... because it made the solution less transparent, more error prone and even more like a hack than it already was

This reverts commit 20391a36.