login-common: Call io_stream_ssl_global_init() early

*-login: Move code to login_anvil_init() Calling this allows plugins that need to talk to anvil make sure they have an anvil connection even if mail_max_userip_connections=0.

*-login: Store user_* passdb fields to client->alt_usernames.

*-login: Allow plugins to hook into client allocation and add module-specific contexts to client.

*-login: Changed -D parameter to mean a more generic login_debug option.

Changed type of internet port values to in_port_t everywhere. Created special SET_IN_PORT setting type for internet port values. Created net_str2port() for parsing internet port values. Removed several atoi() invocations in the process.

login proxy: Added login_source_ips setting. The setting contains a list of IPs/hosts. The setting may be prefixed with "?" character to indicate that only those IPs should be used that exist in the current server (allowing the same config to be shared by multiple servers). The IPs are used round robin as the source IP address when proxy creates TCP connections. This becomes useful when there are a ton of connections from the proxy to the same destination IP, because TCP ports run out after ~64k connections.

Use "tokenlogin" socket name (instead of "token-login") after all. Auth code has special checks for '-', which breaks "token-login" and fixing it is rather annoying.

Added support to perform token-based service process authentication. Creates hidden SASL method DOVECOT-TOKEN. This method is not available on the normal auth login socket and thus never presented to clients. Creates new auth socket type 'tokenlogin'. This otherwise normal login socket only offers authentication using the DOVECOT-TOKEN mechanism. Creates new token-login directory in base_dir to separate token logins from normal logins. This directory is otherwise completely identical to the normal login dir, i.e. it contains sockets for the service backends, used to chroot login processes to, etc. Makes default login socket configurable. Performs some minor changes to src/login-common to build very sparse protocols, e.g. avoid the need to implement methods that are not needed.

Moved ssl_* settings from login-common to lib-master. This allows creating other SSL servers more easily.

login: Use AUTH_REQUEST_FLAG_SUPPORT_FINAL_RESP if protocol supports it.

login: Minor potential authentication fix when service_count>1

login: Added -R <dir> parameter to write pre-login rawlogs to given directory.

login-common API redesign so that the library doesn't refer to nonexistent variables.

login: Keep binary-specific defaults in a struct. --HG-- branch : HEAD

login: If proxy returns ssl=yes and no port, switch port to imaps/pop3s. --HG-- branch : HEAD

*-login: Disconnect from auth server after idling for a minute. --HG-- branch : HEAD

login-common: Renamed common.h to login-common.h --HG-- branch : HEAD