interactive selection of installer

[katakombi]

After concise investigation it seems impossible to reliably retrieve the installer binary for a GOG game. Reasons:

• inconsistent naming (also due to multiple language support)

Solution:

• show users a selection and let them choose

[katakombi]

NOTE: in contrary to #12 we do not want this for dolmades in general. Otherwise they would not be auto-installable any longer!