docs: fix usage of 'onto'

http://www.uhv.edu/ac/newsletters/writing/grammartip2009.07.01.htm
(and several other sites) give hints that 'onto' is best used if
you can also add 'up' just before it and still make sense. In many
cases in the code base, we really want the two-word form, or even
a simplification to just 'on' or 'to'.

* docs/hacking.html.in: Use correct 'on to'.
* python/libvirt-override.c: Likewise.
* src/lxc/lxc_controller.c: Likewise.
* src/util/virpci.c: Likewise.
* daemon/THREADS.txt: Use simpler 'on'.
* docs/formatdomain.html.in: Better usage.
* docs/internals/rpc.html.in: Likewise.
* src/conf/domain_event.c: Likewise.
* src/rpc/virnetclient.c: Likewise.
* tests/qemumonitortestutils.c: Likewise.
* HACKING: Regenerate.

Signed-off-by: Eric Blake <eblake@redhat.com>

python/libvirt-override.c

@@ -4,7 +4,7 @@
  *           entry points where an automatically generated stub is
  *           unpractical
  *
- * Copyright (C) 2005, 2007-2012 Red Hat, Inc.
+ * Copyright (C) 2005, 2007-2013 Red Hat, Inc.
  *
  * Daniel Veillard <veillard@redhat.com>
  */
@@ -5084,7 +5084,7 @@ libvirt_virEventRegisterImpl(ATTRIBUTE_UNUSED PyObject * self,
     updateTimeoutName = py_str(updateTimeoutObj);
     removeTimeoutName = py_str(removeTimeoutObj);
 
-    /* Inc refs since we're holding onto these objects until
+    /* Inc refs since we're holding on to these objects until
      * the next call (if any) to this function.
      */
     Py_INCREF(addHandleObj);