Make language strings (msgids) consistent

[matsduf]

Most msgid strings in the PO files have en consistent structure and work the same way as the msgid strings in Zonemaster-Engine. There are, however, a number of exceptions that make the handling of the PO files more complex.

• The msgid should end with a normal, printable character, neither with white space nor line feed.
• The arguments should be given with variables with names to make it possible to understand what kind of data it is.
• The msgid strings should not contain tabulator characters.
• There should not be any msgid strings that are just language unrelated strings.

Message ending with line feed:

msgid ""
"Warning: setting locale category LC_MESSAGES to %s failed (is it installed "
"on this system?).\n"
"\n"

Messag with one character argument:

msgid "%8s\t%5d entries.\n"

Messages that cannot be translated:

msgid "======= "

msgid "========= "

Message ending with several white space character. Is the number of such important?

msgid "Testcase       "

[matsduf]

Replaced by #330