CLEANUP: general: get rid of all old occurrences of "session *t"

All the code inherited from version 1.1 still holds a lot ot sessions
called "t" because in 1.1 they were tasks. This naming is very annoying
and sometimes even confusing, for example in code involving tables.
Let's get rid of this once for all and before 1.5-final.

Nothing changed beyond just carefully renaming these variables.
diff --git a/include/proto/proto_http.h b/include/proto/proto_http.h
index 2c8b062..9653d8b 100644
--- a/include/proto/proto_http.h
+++ b/include/proto/proto_http.h
@@ -63,30 +63,30 @@
 #define HTTP_IS_TOKEN(x) (http_is_token[(unsigned char)(x)])
 #define HTTP_IS_VER_TOKEN(x) (http_is_ver_token[(unsigned char)(x)])
 
-int process_cli(struct session *t);
-int process_srv_data(struct session *t);
-int process_srv_conn(struct session *t);
+int process_cli(struct session *s);
+int process_srv_data(struct session *s);
+int process_srv_conn(struct session *s);
 int http_wait_for_request(struct session *s, struct channel *req, int an_bit);
 int http_process_req_common(struct session *s, struct channel *req, int an_bit, struct proxy *px);
-int http_process_request(struct session *t, struct channel *req, int an_bit);
+int http_process_request(struct session *s, struct channel *req, int an_bit);
 int http_process_tarpit(struct session *s, struct channel *req, int an_bit);
 int http_wait_for_request_body(struct session *s, struct channel *req, int an_bit);
 int http_send_name_header(struct http_txn *txn, struct proxy* be, const char* svr_name);
 int http_wait_for_response(struct session *s, struct channel *rep, int an_bit);
-int http_process_res_common(struct session *t, struct channel *rep, int an_bit, struct proxy *px);
+int http_process_res_common(struct session *s, struct channel *rep, int an_bit, struct proxy *px);
 int http_request_forward_body(struct session *s, struct channel *req, int an_bit);
 int http_response_forward_body(struct session *s, struct channel *res, int an_bit);
 
-void debug_hdr(const char *dir, struct session *t, const char *start, const char *end);
-void get_srv_from_appsession(struct session *t, const char *begin, int len);
-int apply_filter_to_req_headers(struct session *t, struct channel *req, struct hdr_exp *exp);
-int apply_filter_to_req_line(struct session *t, struct channel *req, struct hdr_exp *exp);
+void debug_hdr(const char *dir, struct session *s, const char *start, const char *end);
+void get_srv_from_appsession(struct session *s, const char *begin, int len);
+int apply_filter_to_req_headers(struct session *s, struct channel *req, struct hdr_exp *exp);
+int apply_filter_to_req_line(struct session *s, struct channel *req, struct hdr_exp *exp);
 int apply_filters_to_request(struct session *s, struct channel *req, struct proxy *px);
-int apply_filters_to_response(struct session *t, struct channel *rtr, struct proxy *px);
-void manage_client_side_appsession(struct session *t, const char *buf, int len);
-void manage_client_side_cookies(struct session *t, struct channel *req);
-void manage_server_side_cookies(struct session *t, struct channel *rtr);
-void check_response_for_cacheability(struct session *t, struct channel *rtr);
+int apply_filters_to_response(struct session *s, struct channel *rtr, struct proxy *px);
+void manage_client_side_appsession(struct session *s, const char *buf, int len);
+void manage_client_side_cookies(struct session *s, struct channel *req);
+void manage_server_side_cookies(struct session *s, struct channel *rtr);
+void check_response_for_cacheability(struct session *s, struct channel *rtr);
 int stats_check_uri(struct stream_interface *si, struct http_txn *txn, struct proxy *backend);
 void init_proto_http();
 int http_find_full_header2(const char *name, int len,