* "Return true/false" is replaced with "Return ``True``/``False``"
if the function actually returns a bool.
* Fixed formatting of some True and False literals (now in monospace).
* Replaced "True/False" with "true/false" if it can be not only bool.
* Replaced some 1/0 with True/False if it corresponds the code.
* "Returns <bool>" is replaced with "Return <bool>".
This is a wholesale reorganization and editing of the email documentation to
make the new API the standard one, and the old API the 'legacy' one. The
default is still the compat32 policy, for backward compatibility. We will
change that eventually.
