Add autocentering of overview

Work funded by Tuscany Region - SITA. Contract "Support to the use
of GFOSS (Geographic Free and Open Source Software) Desktop tools"
(CIG Z3B06FA6D7).
Add unit test for autocentering of overview

Work funded by Tuscany Region - SITA. Contract "Support to the use
of GFOSS (Geographic Free and Open Source Software) Desktop tools"
(CIG Z3B06FA6D7).
Add SIP and Python unit test for overview autocentering.

Work funded by Tuscany Region - SITA. Contract "Support to the use
of GFOSS (Geographic Free and Open Source Software) Desktop tools"
(CIG Z3B06FA6D7).
Fix overview autocentering: always center, not only when the overview is not visible.

Work funded by Tuscany Region - SITA. Contract "Support to the use
of GFOSS (Geographic Free and Open Source Software) Desktop tools"
(CIG Z3B06FA6D7).
Add an update of overview on centering mode switch
Make sure updateFields() is called before setDisplayField for new vector layers (fix #8311)
Fix indexOf checks in setDisplayField, make sure they are case insensitive
[Plugin Installer] Remove hardcoded 2.0 version in order to use the native 2.0
[postgres] do not update feature count if it was not set before
Merge pull request #804 from nyalldawson/bug_8311

Fix some bugs relating to display fields for new vector layers (fixes #8311)
IT GUI translation almost finished
Upadated list of IT translators
fixes "Add to Overview" action, also removes shortcut
update TRANSLATION ja
update fr translation
Merge pull request #865 from yoichigmf/forpullreq

update TRANSLATION ja
Merge pull request #864 from Jean-Roc/traduction_ui

update fr translation
german translation update
Updated QgsFields docs, moved some code into .cpp
indentation update