Read environment variables from .env file

Changes for 0.009 - 2024-03-09T23:29:28+01:00

• Reverse the order in which dotenv files are read from var ENVDOT_FILEPATHS.
• Reindent Changes file.
• Get ENVDOT_FILEPATHS variable's name from method get_envdot_filepaths_var_name().
• Change DEFAULT_OPTION_READ_FROM_STDIO to DEFAULT_OPTION_READ_FROM_STDIN.
• Change var from $dotenv_filepath_var to $var_name.
• Add test to test synopsis example of environment override.