AGS games can have multiple languages by providing
additional translations as .tra files. The language
selection is done by setting the config "translation"
key to the tra file name. This means that we cannot
easily use the standard ScummVM language selection
for this purpose as the tra file name may not map
to language names easily.
The approach in this commit does something similar
to the original games by detecting at runtime the
available tra files.
Thierry Crozat
Paul Gilbert