[transform] xfig: finally support object transformation via draw_object()

a given matrix was turned to a g_warning() in 2010 with commit
cd3b2398704b7c08b9c3e42cd32bac2c78dc7370 but forgotten in 2013 when
DiaTransformRenderer was introduced with commit
507f0cbc725115d14933372272bd67569bee367f
Bug 737889 - Dialog referring to a choice that doesn't exist

There is "Best Fit" (coming from GTK+ but select all is not necessary before.
xfig: s/of of/out of/