(! means necessary / blocker for releasing v3)

# General changes:
! Update all files with new license info

# Github:
! Update branch names on Github (rc3 -> v3)

# Website:
! Update website:
  o Finalize changelog
  o Post announcement
  o Update installation instructions
  o Update news
  o Update code samples of DMRG and contraction on the main page
  o Remove " ITensor version 3 has not been released yet. This documentation is a preview only."

! Send email

# Final Release Checks
  ! Fresh install with new options.mk file compiles
  ! Jenkins is passing
  ! All sample codes compile and run and are up to date