Make reported exception stack-traces more concise

Reported exceptions stack-traces are too long, they sometimes take more then two screens. It makes report less readable.

It would be nice if they are shorter.

For example if they are generated to html:

• then they can be written inside textarea or another block, frame with predefined height, so one will be able to scroll in such a block to reveal full stack-trace
• or something like Twitter Bootstrap collapse can be employed.