#17700: update the curses HOWTO for 3.x
#17700: merge with 3.3
#17841: remove missing codecs aliases from the documentation.  Patch by Thomas Fenzl.
#17841: merge with 3.3.
I was confused before.  It's correct to not call .close() inside the with
statement, but add a comment that clarifies the purpose of the code.
Merge 3.3
#17927: Keep frame from referencing cell-ified arguments.