Fixed errors in translated strings

Such errors can be detected with tools like Qt Linguist, which shows a
red exlamation mark.

• If msgid ends with ":", msgstr must end with ":" too, and the same for other interpunctation and white space
• If msgid contains an accelerator "&", msgstr must have an accelerator too
• If some words in msgid are separated by "/", this should also be the separator in msgstr
• Most important: Replacements %1, %2, ... in msgid must have the same replacements in msgstr.