Add window operator
Add tests for window operator
Change text on window tests
Merge pull request #24 from ValeriyKopylov/window

add Window operator
add tracing hooks
add create and print. redo lift.

arrrggg pulled a thread in lift and it unravelled..
print fixes
more lift fixes
fix travis script
Merge pull request #25 from kirkshoop/liftandcreate

Redo lift and add create, tracing hooks