REORG: include: move task.h to haproxy/task{,-t}.h

The TASK_IS_TASKLET() macro was moved to the proto file instead of the
type one. The proto part was a bit reordered to remove a number of ugly
forward declaration of static inline functions. About a tens of C and H
files had their dependency dropped since they were not using anything
from task.h.
diff --git a/src/tools.c b/src/tools.c
index 6dda8aa..fd77795 100644
--- a/src/tools.c
+++ b/src/tools.c
@@ -46,12 +46,12 @@
 #include <haproxy/hlua.h>
 #include <haproxy/listener.h>
 #include <haproxy/namespace.h>
+#include <haproxy/task.h>
 #include <haproxy/tools.h>
 #include <proto/applet.h>
 #include <haproxy/proto_udp.h>
 #include <proto/ssl_sock.h>
 #include <proto/stream_interface.h>
-#include <proto/task.h>
 
 /* This macro returns false if the test __x is false. Many
  * of the following parsing function must be abort the processing