import open from io instead of builtins

wetb/fast/fast_io.py

wetb/hawc2/Hawc2io.py

wetb/hawc2/ae_file.py

wetb/hawc2/ascii2bin/ascii2bin.py

wetb/hawc2/ascii2bin/pandas_dat_ascii2bin.py

wetb/hawc2/at_time_file.py

wetb/hawc2/cmp_test_cases.py

wetb/hawc2/htc_file.py

wetb/hawc2/log_file.py

wetb/hawc2/pc_file.py

wetb/hawc2/sel_file.py

wetb/hawc2/shear_file.py

wetb/hawc2/simulation.py

wetb/hawc2/tests/test_htc_file.py

wetb/hawc2/tests/test_logfile.py

wetb/hawc2/tests/test_shear_file.py

wetb/prepost/Simulations.py

wetb/prepost/hawcstab2.py

wetb/prepost/misc.py

wetb/prepost/prepost.py