Iterates through a model
<clutter-model-iter> is an object used for iterating through all
the rows of a <clutter-model>. It allows setting and getting
values on the row which is currently pointing at.
A <clutter-model-iter> represents a position between two elements
of the sequence. For example, the iterator returned by
clutter-model-get-first-iter represents the gap immediately
before the first row of the <clutter-model>, and the iterator
returned by clutter-model-get-last-iter represents the gap
immediately after the last row.
A <clutter-model-iter> can only be created by a
<clutter-model> implementation and it is valid as long as the
model does not change.
<clutter-model-iter> is available since Clutter 0.6