#21079: is_attachment now looks only at the value, ignoring parameters.
Merge: #21079: is_attachment now looks only at the value, ignoring parameters.
#21091: make is_attachment a method.

Since EmailMessage is a provisional API we can fix API bugs in a
maintenance release, but I used a trick suggested by Serhiy to
maintain backward compatibility with 3.4.0/1.
Merge: #21091: make is_attachment a method.
Issue #22359: Remove incorrect uses of recursive make.  Patch by Jonas Wagner.
Doc: remove invalid uses of ":option:" which will emit warnings in Sphinx 1.3.
merge with 3.4