Translation for "B" impossible in xboard 4.9.0-pre2

Hi,

the English string "B" appears twice in the translations, with these
meanings:

"B" = "Bishop"
"B" = "Bold"

In German, that would translate to:

"L" (for "Läufer")
"F" (for "Fett")

Since I cannot translate "B" with both "L" and "F" at the same time,
this is impossible and should therefore be fixed in the code.

Instead of using "B" as the source string, you should use "B (chess
piece)" and "B (bold)" as source texts. These provide enough context so
that they can be translated well. The code dealing with these strings
then needs to be adjusted to strip off everything starting with the
first space character. Or some similar solution.

Thanks,
Roland