flake8 --select E713, semi-manual fixing

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

Allowing future use with upcoming VideoStream

Signed-off-by: Pierre Mazière <pierre.maziere@gmx.com>

Signed-off-by: Pierre Mazière <pierre.maziere@gmx.com>

Change every mention of MAINTAINER to avoid future issues.

And add restrict_level helper method.

It's hard to reproduce the bug, I had it for a very short time, and
didn't think of saving the HTTP responses.