Verify new object creation in Ason_operate

Signed-off-by: Casey Dahlin <casey.dahlin@gmail.com>
Add parse method to ason module

This exposes ason_read directly

Signed-off-by: Casey Dahlin <casey.dahlin@gmail.com>
Fix some leaks in Ason constructor

Signed-off-by: Casey Dahlin <casey.dahlin@gmail.com>
Add bind variables to ason.parse

You can now specify keyword arguments after the expression in ason.parse, which
will be converted to ASON and evaluated within the expression.

Signed-off-by: Casey Dahlin <casey.dahlin@gmail.com>
Iterators

We can now iterate Ason values with python iterators. This also makes casting
to dict or list work for objects, lists, unions, etc.

Signed-off-by: Casey Dahlin <casey.dahlin@gmail.com>