TWAIN string aren't correctly handling localized content... [sf#20]

[kolomiets]

Reported by mlmcl on 2016-09-02 18:29 UTC TWAIN strings (TW_STR32, TW_STR64, etc) don't correctly handle codepages on Windows, which causes problems when the contents pf those strings are localized. The code was using UTF8 encoding on Windows, and it was using strings when it should have been using byte arrays...