mention improvements to Schubert2 in the changes section for 1.6
document the Isotropic option to flagBundle in Schubert2

refer to the paper of Grayson, Seceleanu, and Stillman

remove the obsolete file pushfor.m2, since it's a package now, called PushForward

eliminate the warning message about shadowing the symbol PushForward by using the name of the package PushForward instead
(users will have to write "global PushForward" instead of "PushForward" on occasion)
import PushForward into Schubert2 instead of exporting it
the symbol will still be available in the dictionary Packages