Ftw.testbrowser

------------------

- ContentTreeWidget: support filling objects as values.
[jone]

------------------

- Implement `logout` on browser, logout before each login.
[jone]

------------------

- Add `cookies` property to the browser.
[jone]

------------------

- Fix multiple wrapping on browser.forms.
[jone]

------------------

- Implement archetypes datetime widget form filling.
[jone]

------------------

- Fix encoding problems when posting unicode data directly with Browser.open.
[jone]

- Support form filling with bytestrings.
[jone]

- Fix form filling with umlauts.
[jone]

- Fix form fill for single select fields.
[jone]