Pattern support in header configuration

Hi,

First: good job with the addon, very useful :)

I've added a new feature we needed to modify headers in a fork I created. It allows a new configuration parameter for each header, and only if the pattern matches the url it will apply the header change.

The commit includes a couple of commits with the following changes:
- pattern feature
- build script updated to new xpidl scripts
- it also modifies source code indentation to use always tabs. it was mixing spaces and tab and my editor changed all of them...

Regards,
Jorge