* The mail listing's endpoint and format has changed
* Read message's raw email format
* iter_threads returns one thread per message instead of only one thread

flake8 --select W391,E302,E301,E304

autopep8 can't fix W391 even though it claims it can.
Fixed using a simple custom script.

weboob.tools.browser -> weboob.deprecated.browser
weboob.tools.parsers -> weboob.deprecated.browser.parsers
weboob.tools.mech -> weboob.deprecated.mech
weboob.browser2 -> weboob.browser
weboob.core.exceptions -> weboob.exceptions

Also, the new tree for browser2 is:

weboob.browser: import weboob.browser.browsers.* and weboob.browser.url.*
weboob.browser.browsers: all browsers (including PagesBrowser and LoginBrowser)
weboob.browser.url: the URL class
weboob.browser.profiles: all Profile classes
weboob.browser.sessions: WeboobSession and FuturesSession
weboob.browser.cookies: that's a cookies thing
weboob.browser.pages: all Page and derivated classes, and Form class
weboob.browser.exceptions: specific browser exceptions
weboob.browser.elements: AbstractElement classes, and 'method' decorator
weboob.browser.filters.*: all filters