On com_pgrid, added a function to the pgrid.js file to allow adding items to the toolbar, which is necessary for the com_mailer email button that is added dynamically to select grids. This version of pgrid is now taking a separate direction from the individually packaged pgrid jquery plugin due to naming changes that will not be compatible with pines. 

On com_mailer, added in a conditional config option to limit the number of rows in a grid that can be selected per email transaction.