FCK page picker: only mount the current virtual site by default. A drop down or site picker should be made available as an option in the toolbar

The FCK page picker is by default listing all virtual sites. Some customers have more than 500 virtual sites (e.g: our beta customer such as the EPFL). Listing 500 virtual sites on the first level will be quite an issue.

By default (90% use case) editors wants to usually make some cross-reference in the current virtual site. So we could limit the default view ot the current site. Then we could envision having a "Virtual site picker" in the toolbar in order to mount another virtual site. We could then perhaps define if the mount will be permanent or temporary (option when mounting the toolbar).

We could perhaps also directly expand the current path on the current page. most of the time editors wants to make some cross-reference on sister or children pages. So this could also help minize the number of clicks required in order to make a cross-reference.