Draft NOTES for 1.13.0

@mglukhovsky can you please review?

@danielmewes @Tryneus @mlucy @danielmewes @neumino @srh Please also take a look to make sure I haven't mis-characterized some of your fixes.
I talked to @danielmewes. There's some type of data that doesn't get loaded into memory anymore. I think this description is fine.