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.

--- a/src/auth/auth-request.h	Fri Sep 14 21:31:45 2012 +0300
+++ b/src/auth/auth-request.h	Fri Sep 14 21:48:45 2012 +0300
@@ -73,6 +73,7 @@
 	unsigned int client_pid;
 	unsigned int id;
 	time_t last_access;
+	pid_t session_pid;
 
 	const char *service, *mech_name, *session_id;
 	struct ip_addr local_ip, remote_ip;
@@ -157,6 +158,8 @@
 			      const char *key, const char *value);
 bool auth_request_import_auth(struct auth_request *request,
 			      const char *key, const char *value);
+bool auth_request_import_master(struct auth_request *request,
+				const char *key, const char *value);
 
 void auth_request_initial(struct auth_request *request);
 void auth_request_continue(struct auth_request *request,