window functions

[piccolbo]

none of the window functions work.
Excited by the announcement that SparkSQL now supports window functions I endeavored to make sure that they are supported in dplyr-spark. Since they are supported in dplyr. I created a new test file with the dplyr window-function examples in the linked to document above. None of the generated queries work in sparkSQL. I suspect these window function extensions are not completely standard. Need to investigate further.

[piccolbo]

some of these problems depend on tidyverse/dplyr#1060

[piccolbo]

Passes the dplyr tutorial. We can close this as soon as dplyr#1060 closes.

[piccolbo]

By the way we monkey patched #1060 so this is open only to remove the monkey patch when it's time