Merge branch 'master' into invite-dialog-jitsi

Fixes NullPointerException in conference invite dialog (ongoing work on
fixing missing contacts in invite dialog).
Merge branch 'master' of https://github.com/jitsi/jitsi
Commit from translate.jitsi.org by user emcho.: 1458 of 1458 strings translated (0 fuzzy).
Merge branch 'master' of https://github.com/jitsi/jitsi
New files added from translate.jitsi.org based on templates
Commit from translate.jitsi.org by user ibauersachs.: 1458 of 1458 strings translated (0 fuzzy).
Commit from translate.jitsi.org by user emcho.: 1458 of 1458 strings translated (0 fuzzy).
Commit from translate.jitsi.org by user emcho.: 1458 of 1458 strings translated (0 fuzzy).
Ignore local changes on .gitignore
And again ... wth
Employs packet loss concealment (PLC) for the Opus and SILK audio codecs.
Change install new version warning as suggested by David Bolton on dev
Renames and moves the cusax account property from cusax.xmppAccountID to
cusax.XMPP_ACCOUNT_ID.
Increments version minor to 3 (i.e. nightly version prefix is not 2.3)
Missing language property

Specified in src.net.java.sip.communicator.impl.gui.main.menus.ToolsMenu
for when the user clicks Tools / Create a conference call... and there
is no configured conferencing account.