Add error message dialogs, Add CCW winding flag

[ruby0x1]

Error messages rather than silent logging:

CCW Flag for exporting to non CW engines:

Also:

• I bumped the versions - tested only on Blender-2.75
• The diff between the scripts is a commit comment below, since the file is new it's less clear.

[ruby0x1]

Also realized I should have checked existing PR's! There seems to be some overlap on the error messages.

[shakesoda]

I'm not entirely sure an option to reverse winding is a good idea. I had originally implemented that too, but then I ran into the issue of my IQM models not having consistent winding and there being no way to tell - not good. Instead I reverted that change and just change the winding in the loader, since that's just a matter of swapping triangle indices 2/3.

+1 for better error reporting, though.

[ruby0x1]

Hmm curious @shakesoda thanks for the thoughts. I reversed the full order not just 2/3, which may matter to why the indices being weird.

I agree about the winding being unknown from file to file, but adding an extra byte was a bit overreaching for discussion. It's probably good to see what the goals/vision are - I would be ok with it being forced but changing windings on load time adds huge expense, but it also demeans the goals of the library directly by slowing it down and adding importer complexity, increasing the chances of error etc.

I think the option is innocuous enough as a starting point for discussion, though!