Worthy to note: Chained Payment not implemented

Hi,

perhaps its worthy to note, that this plugin doesn't fullfill
the paypal requirements for a site which hosts crowdfunding projects for users.

the plugin has only on paypal account, which is sufficent
if site-owner is the same as project-owner.

For chained payment you neet two accounts, and special configuration for who is feepayer and commisson.
we have serious problems with paypal as it couldn't approve our fundraising site.

i extended the plugin to support this mechanism.