trunk: align to edge of anchor moves anchor object as well

In Inkscape trunk >= 12414, the commands to align to the opposite side of a chosen bbox edge of an anchor object aligns (i.e. moves) the anchor object as well.

This report is based on this discussion on the mailing list 'inkscape-devel':
<http://thread.gmane.org/gmane.comp.graphics.inkscape.devel/40826/focus=40841>

Steps to reproduce:
1) launch inkscape with default preferences
2) open attached sample file
3) select all objects (Ctrl+A) on the current layer 'test'
4) open 'Align & Distribute' (Ctrl+Shift+A)
5) choose 'Relative to: Smallest object'
6) click on 'Align left sides to right side of anchor'

Expected result:
The anchor object (the smallest among the selected objects) stays fixed, and the rest of the selected objects are aligned horizontally with their left edges to the right edge of the bbox of the anchor object
(expected result depicted on locked layer 'r12412' in sample SVG, in the middle of the page)

Actual result:
The anchor object is aligned horizontally too, together with the rest of the selected objects, with its left edge to the position of the right bbox edge of the anchor object at its original position.
(unexpected result depicted on locked layer 'r12414' in sample SVG, on the far right side of the page)

Regression introduced with the refactoring changes in r12413/r12414,
tested and confirmed on Ubuntu 12.10 (64bit, VM) and OS X 10.7.5, comparing the results of r12412 and r12414/r12415.