#881 npambulant problems on Ubuntu 14.04 (both 32/64 bit)

[Kees Blom]

The npambulant plugin (2.6) does not place the elements (images, (smil)text, etc) correctly, they all go to the top-left corner.
This only happens on a Virgin Ubuntu 14.04 (both 32/64 bit).

When on Ubuntu 14.04 Virgin 64 bit the plugin is build from ambulant-2.6.tar.gz
(after installing all needed support packages by running 'sudo precheck-ubuntu debinstall'), the plugin does not run at all.

[Kees Blom]

Fixed in rev. 9141.
Problem was in node_iterator.h, 'operator*' where 'true' was returned whenever the member variable 'm_move' contained the address of the function
const_tree_iterator::down.
However, in case when this file was used to compile sources for different
dynamic (plugin) libraries, this address is not run-time unique:
there may be several addresses in core all pointing to copies the same code.
The solution is to register this fact (whether or not 'm_move' holds a pointer to 'down') using an auxiliary variable 'is_down'.