OSM provider: make the looooooooooong lines that create triggers actually readable
[FEATURE] new OpenStreetMap data access API and GUI

The idea is to replace the current OSM provider+plugin by this new code. Differences from old code:
- read-only access - without editing and upload support
- no special provider (using SpatiaLite provider)
- underlying OSM topology accessible from API
- download using Overpass API: fast, customizable, nearly unlimited download
- OSM XML files have to be first imported to a Sqlite3 database, then SpatiaLite layers can be exported
Add file headers, do not report error in case there are no spatial tables in SpatiaLite database
indentation update
german translation update
Old unmaintained OpenStreetMap support is dead. Long live new OpenStreetMap support!
Add new, duplicate and delete composer to iface

- Works via QgsComposerView, which is already exposed in iface