Remains: flipping all "back" background textures along the 45 deg axis.
That is, flip both x and y on all _back textures, to make dds unified cubemaps compatible with 6-file ones.
NOTE: do not comment debugging output, which is useful.
Rather, a proper debugging API should be placed somewhere and all logging should be done with that API, each log message should have a level (debug, info, warning, error), and a config setting should define the desired logging level.