[WIP] [Feature] exception tracing tool

This is a nice layouted exception tracing and debugging tool. Instead of plain output the exception on a white page, display a dialogue with additional debugging features.

- [x] Trace exceptions with a nice dialogue
- [x] Trace ~~warnings~~ errors with a nice dialogue
- [x] Link file-no to the respective code in a lightbox
- [x] Link lines in lightbox to github
- [ ] Filter critical files (e.g. localconfig.php) from output
- [x] Filter critical informations (e.g. database host/user/password, secret, TL_ROOT) from output
- [ ] Only output file sources when BE user is logged in

Here are some screenshots:

![trace1](https://cloud.githubusercontent.com/assets/343404/2815991/b5d4eef6-cec2-11e3-96da-021348869363.png)
![trace1b](https://cloud.githubusercontent.com/assets/343404/2815992/b5ec9a92-cec2-11e3-8c1b-0f875443fd7a.png)
![trace2](https://cloud.githubusercontent.com/assets/343404/2815993/b5ff6140-cec2-11e3-99c0-660d77f4e9de.png)
![trace2b](https://cloud.githubusercontent.com/assets/343404/2815994/b5ff93a4-cec2-11e3-9a2b-cb655d979476.png)
![trace3](https://cloud.githubusercontent.com/assets/343404/2815995/b600ed8a-cec2-11e3-9ffe-308df558d47c.png)

The main problem are warnings, which are not traced at the moment:

![trace4](https://cloud.githubusercontent.com/assets/343404/2815996/b600fba4-cec2-11e3-84dd-68bc86ab5010.png)

What do you think about this?