Allow for debug mode on example iframes

[decioferreira]

This change allows a very simple change on the example build, to allow for the examples to be compiled in debug mode.

[gampleman]

I've considered this before, but one of the reasons I'm a bit sceptical of this is that it will change the screenshots - they will now have the debug UI visible in them.

There is however an option in the screenshot producing library that allows you to hide a certain element before taking a screenshot, so perhaps we could use that? In that way the screenshots should look the same in debug mode as they do in normal operation.

[decioferreira]

I take your point. In my use case, I was only using the debug mode to review the messages and state on the examples I was building, so it was not a problem that the screenshots had the debugger element.