[vdr] vdr 1.3.44: more format string checking

I've done a build of vdr 1.3.44 with -Wformat=2. This was noisier than it might be due to some tr() calls; however, in <libintl.h>, I've spotted something of use:

__attribute_format_arg__ (index)

With this added to the prototype for I18nTranslate, a lot of "non-constant format string" warnings are eliminated. I've also found several possible problems, mostly missing format strings. I don't /think/ that any of the missing-format-string ones are exploitable (at least one definitely isn't), but it's better to have them fixed anyway...

Patch attached. This kills all of the format string warnings which I could find.