Fixed titles in newsfile

The first title at the same level of the main releases helps getting a
more regular ToC in the docs main page.
Fixed pickling of exceptions with no pgerror/pgcode set

Fixes ticket #170.
Meaningful connection errors report a meaningful message

Fixes issue #173.
Document that using %, (, ) in the placeholder name is not supported
Document that named cursors don't raise an exception going out-of-bound

See issue #174 for the details.
Really test named cursors in test_scroll_named()
Use bytestrings in infinite dates adapter example

Returning strings would result in unclear tracebacks on Py3 (see ticket #163).
Typo fixes and improvements to new_array_type() docs
Check connection type in lobject init

Fixes ticket #187.
Fixed dealloc of lobject->smode

I put it by mistake into the in the self->conn checked block in the
previous commit.