interactive selection of target binary

[katakombi]

After concise investigation it seems impossible to reliably retrieve the target binary of a GOG game automatically. Reasons:

• lnk-Files resolve case-insensitively to the target binaries
• parameters missing
• multiple binaries, and no clue which one is the proper one
• ...

Solution:

• resolve all .lnk files to their respective .exe/.EXE/.bat/.com files with full path
• check whether the file exists: need to make matches case-insensitively here!
• show users a selection and let them choose

[katakombi]

An individual solution for GOG is unlikely better than to solve this for dolmades in general. Please see please see #12 instead.