Allow behavior customization (API) in custom block pages

[CyberShadow]

Currently, the custom block/delay pages only allow changing the look (skinning), but they do not allow controlling LeechBlock behaviour. It would be nice to have a way to do that.

This would allow customizing LeechBlock to do things like:

• customizing block behavior (timeout duration) beyond the limits of LeechBlock's configuration dialog
• filtering the blocked URLs with a finer method than substring search
• asking me to solve a math equation to proceed to the blocked page

Essentially, the main thing that's missing is a JavaScript function accessible from the page's embedded script, which allows proceeding to the blocked destination page. Setting document.location doesn't work because that just triggers LeechBlock again.

[proginosko]

Thanks for this good suggestion. I'll give some thought to how that could be added in a future version.