Add strusage macro replacement feature.
* common/argparse.c (writechar): New. (writestrings): Add macro replacement feature. (show_help): Remove specialized @EMAIL@ replacement. * configure.ac (GNUPG_NAME, GPG_NAME, GPGSM_NAME): Define. (GPG_AGENT_NAME, DIRMNGR_NAME, G13_NAME, GPGCONF_NAME): Define. (GPGTAR_NAME, GPG_AGENT_INFO_NAME, GPG_AGENT_SOCK_NAME): Define. (GPG_AGENT_SSH_SOCK_NAME, DIRMNGR_INFO_NAME): Define. (DIRMNGR_SOCK_NAME): Define.
- Signed-off-by: Werner Koch <wk@gnupg.org>