#1 A different way to decide to read as resource

[Tim Learmont]

I think that it would be better for XQEngine.parse to
use File.exists() rather than File.isAbsolute() when
trying to decide whether to open the file as a resource
or not.

If the file exists, even if it is a relative path name,
it would be helpful for me (and, I think others) if
XQEngine.parse would open the file, rather than trying
to open a resource by that name (which may fail).

This would make some testing easier, because you could
use relative names and not have to worry about always
supplying an absolute path. It would also allow you to
"override" the version of a file which is in the
classpath if you desire.