deprecates options -c|m|C|i at 66-enable and add option -I. Pass to the new configuration file format at ssexec_env.

The check of the symlink can return true even if lstat return -1, so be sure to only pass if the lstat return 0 and the symlink check return true

allow to use a different version of configuration file than the frontend file if any of -c/m/C is providen. Version symlink point now to the directory instead of the file itself which allow to have extra configuration file

split exlsn_s struct,env_substitute function from execl-envfile to environ.h,add make_env_from_line, env_addkv function