<h3>overlaps function</h3>
Returns 1 if the geometries share space, are of the same dimension, but are not completely contained by each other.

<h4>Syntax</h4>
<pre>overlaps( a, b )</pre>

<h4>Arguments</h4>
a &rarr; geometry
b &rarr; geometry

<h4>Example</h4>
<pre> overlaps( geomFromWKT( 'LINESTRING(3 5 , 4 4 , 5 5 , 5 3)'  ) , geomFromWKT( 'LINESTRING(3 3 , 4 4 , 5 5)' ))   &rarr; returns 1</pre>
<pre> overlaps( geomFromWKT( 'LINESTRING(0 0 , 1 1)'  ) , geomFromWKT( 'LINESTRING(3 3 , 4 4 , 5 5)' ))    &rarr; returns 0</pre>
