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
[Plugin Installer] Remove hardcoded 2.0 version in order to use the native 2.0
pl translation update: small fix
Merge pull request #869 from Cracert/master

Polish translation update
fix warnings
Bumped master version to 2.1.0
debian packaging: update version to 2.1
Merge pull request #852 from borysiasty/installer_v2

[Plugin Installer] Remove hardcoded 2.0 v in order to use the native 2.0
fix crash in coordinate capture plugin
pl translation update
[function help] In strpos() needle is string, not number
Merge pull request #872 from Cracert/tr

Polish translation update
Merge pull request #873 from Cracert/i18n

[function help] In strpos() needle is string, not number
osgeo4w: fix shortcut removal
[FEATURE] Paste features as new vector layer
Paste as - new memory layer name dialog
Save as dialog collapsible OGR options