Missing some default Velocity Context bindings when sending a template mail

For example we should have $xwiki, the velocity tools, etc. What we cannot have it $doc since the mails are now sent from a separate thread. So if users want to use $doc they should it in the their code using the Mail Sender API as in:

#set ($templateParameters = {'velocityVariables' : { 'name' : 'John', 'doc' : $doc }, 'language' : 'en', 'from' : 'localhost@xwiki.org'})