Use 'expression' attribute to specify expression for 'if' and 'for' elements.
Use 'expression' attribute to specify expression for 'if' and 'for'
elements.

Report error when elements doesn't have required attribute.

Refs #385.


git-svn-id: 84a7e9580ef41fb6fdf7e69fc6952b9cdfe895dd@4993 661adc5f-87f8-0310-85d6-9a7b5f58d823

reznikmm/matreshka,reznikmm/matreshka,reznikmm/matreshka,reznikmm/matreshka,reznikmm/matreshka,reznikmm/matreshka