conda v3.19.4 Release Notes

    • improve handling of local dependency information, #2107
    • use install.rm_rf for TemporaryDirectory cleanup, #3425
    • fix the api->conda substitution, #3456
    • error and exit for install of packages that require conda minimum version 4.3, #3726
    • show warning message for pre-link scripts, #3727
    • fix silent directory removal, #3730
    • fix conda/install.py single-file behavior, #3854