ReCaptcha feature
ReCaptcha config from setup script

Added config setting to be available from the ./setup script. Captcha
public and private keys are added in the Features->Security tab, the
captchaLogin is available in the New Server tab where you can enable or
disable reCaptcha for that server.
ReCaptcha https and CSP bug fixes
ReCaptcha error message
Recaptcha bug fixes

Error message for empty captcha "Please enter correct captcha!" and if
the user enters correct captcha but wrong login data it won't be
required to enter it next time.
Make database extension code object oriented
As DBI_Extensions are not classes we can mock them for tests.
Convert database interface to a class
Fix tests by using mock objects of DatabaseInterface
Merge branch 'master' into OOP_DBI
Few renamings that got missed
4.0.2 release
Set MaxNavigationItems value irrespective of it being set earlier
Translated using Weblate (Dutch)

Currently translated at 100.0% (2603 of 2603)
Merge remote-tracking branch 'origin/QA_4_0' into QA_4_0
Missing renamings
Translated using Weblate (Portuguese (Brazil))

Currently translated at 100.0% (2666 of 2666)
Merge pull request #1 from lem9/OOP_DBI

Missing renamings
Some more missing renamings
isSuperuser() is also a part of DatabaseInterface class