Get key value, using Init copy for its default value.

GetBool returns the bool value for key.

GetInt returns the int value for key.

GetUint returns the uint value for key.

Set sets env key value.

SetDefault sets a default value.

SetInt sets an int value.

SetUint sets an uint value.

UNSET is the string returned for values not found in env nor in Defaults either.

Init contains the initial settings.

MBENV is the default env name.

MBENV_CONFIG if set, should be a dir path where to look for ${MBENV}.env file.