[Petal] [BUG] xi:includes don't preserve set variables

[Steve Purkis]

Hi,

This is a bug report for Petal-0.92.  It looks like variables from 
xi:includes are not being preserved across files.  This makes factoring 
out common chunks of functionality very difficult.  Here's a test 
scenario:

   index.html:
	<xi:include href="./foo.html"/>
	foo (index.html): $foo

   foo.html:
	<?var name="set: foo some_true_value"?>
	foo (foo.html): $foo

Regards,
-Steve