Fix potential bug in requestmethod where you cannot specify None for a keyword argument where None is not the default

http://www.zope.org/Collectors/Zope/2308.

Collector #2300: delimit *all* headers with CRLF; accumulated_headers and appendHeader use \n for delimeters and never get corrected on output

headers of plain html files served from Zope3 resource directories.

Also cleanup whitespace in CHANGES.txt.

not send the expected copy/move events.

Note: Tests live in OFS.tests.

- Add a request method decorator to AccessControl, creating decorators that limit a method to one request method only.
- Protect various security-setting-mutators with a POST-only decorator.

Add a 'method' key to the HTTPRequest.other, containing the uppercased REQUEST_METHOD. This makes HTTPRequest a little bit more compatible with Zope3 IHTTPRequest.

Use a decorator to save and restore thread-local state.

No longer opens a zodb connection every time a ProductDispatcher is looked up, forward ported from zope 2.10 branch r72990 and five 1.5 branch r72986.

Fix for #2288: do not quote + and @ characters when forming BaseRequest and HTTPRequest URL variables

Raise SyntaxError when encountering invalid PythonScript headers.