Release AmberTools

cd $AMBERHOME
bash mkrelease_at 
# pytraj files will be cythonized during this process. 
# ISRELEASE will be changed from `False` to `True`
# users do not need Cython to install pytraj
# cythonized (cpp) file will be included in AmberTools*tar file 

Notes: make sure to add cythonized cpp files to git repo of amber{number}-with-patches branch