If new countries was supplied on CLI the custom-mirrors.json would reflect the change.

removed -g

renamed only_country to country_pool
commented obsolete functions

refactored signatures

removed ':' colon from HLP_ARG_GENERATE
removed options from the OVERRIDE_OPT
added number as optional to MODIFY_DEFAULT with ref to translated text

fixed error in Makefile
added to gitignore

number is optional
internal defaults to 0
can be substituted with -g (backwards compatibility)

some are mutual exclusive

change disable_custom_config - add call to modify_config