Update develop version to 3.7.1-develop
corrected a grammar mistake
Merge pull request #208 from meandor/develop

Corrected a grammar mistake
Avoid MySQL password flush when generation configuration files at installation process (fix #211). Disable cache on install pages.
Add better image cache handling to avoid manual browser cache refresh on album art change
Fix travis build on album art
Fix http-rang streaming
Declare apache_request_headers and getallheaders if missing (#212)
Avoid Content Range requests on democratic stream
Get right insertion order for same level songs in democratic playlist
Avoid mouse over table size change and world wrap track / album /artist name on Reborn theme
Add git pull update from web interface
Recheck version after autoupdate
Add session id on votes (fix #173) and a new option to clear expired sessions votes (#178)
Add merge on tags (fix #120)
Set classic theme box size to 95% (fix #221)
Support multi level tag merge
Ger tranlation + mo's, po's & pot updated due to last changes +

small fix to make the "Return" link on Update Page more informative
Fixes #198 with an Add to New Playlist button.

Added an Add to New Playlist button. It calls the SavePlaylist()
Javascript function that fetches the song_id from the jplaylist
on the client side, then makes an Ajax call.

I had to modify the song item_type so that the item_id would be
all added accordingly. Adding a new item_type didn't work for
unknown reason, the new item_type case never being picked up.
Partially added the collapsing feature of the left bar

Added a toggle switch on the left bar sub menus. Added a small icon
alongside the submenu name. It currently toggles the submenus correctly
and changes the icon orientation. However, the state of the menu isn't
kept in memory, therefore changing to another sidebar (from home to
admin for instance) doesn't keep the current display settings.

By default, all menus are expanded.
Fix image requested name when unknown extension