various l10n updates (pt6) (#3128)

* l10n: small typo fix

* l10n: edit-circuit extend some more possible l10n strings

* l10n: make action menu in *circuits* translatable

* l10n: make action menu in *provider* translatable

* l10n: small fixup and addition for *circuit*

Split of again strings with variables inside, add one new string.

* l10n: small fixup and addition for edit-provider*

Split of more strings with variables inside.

* l10n: more strings in edit-logical-circuit.php

A few more strings that can be switched to l10n strings.
Uniform mixed intendation to spaces.

* l10n: minor update on login/index

Once more split of strings with variables inside.

* l10n: minor update on class.DNS

Split of also here strings with variables inside.

* l10n: adding more strings in class.User

functions/classes/class.User.php has already l10n marked strings for the
various result windows and also a few existing string for the logging.
Adding more l10n markers so we have more translatable strings in the
end.

Yes, the log messages don't have currently some l10n mechanism so the
logs are currently all written in the plain native language from the
source files, but as already some strings prepared and at some day users
will ask for a option to write the log messages in their own language
different from English it's hopefully useful in the long term that
strings are pepared here.

* l10n: Update German translations

Update the po file and also the binary message catalog for German after
reworking various source files.