Better messages when client errors

[silasary]

Slightly improves the error messages

I currently assume that any stack trace involving UT is probably UT's fault. I can't think of a reason that wouldn't be true.

Regardless of whether UT is involved, posts the full stack trace, not just the text parameter of the exception.

[nicopop]

1. the way the popup work right now does not make it easy to copy and paste the error message path.
   maybe a copy to clipboard button could be helpful.
   that or a way to select the text to allow ctrl c
2. when the window width is too small the errors path can go offscreen and there's no scrolling possible

[silasary]

While I agree with both of these, keep in mind that all I'm doing is overriding the contents of this box:

I'm not quite sure how much I can push the popup without breaking AP's expectations, nor am I confident enough with kivy to do so.

[nicopop]

fair enough