Template on shader types, rather than count. This allows the compiler to enforce using the correct VAO for the shader and PaintMode. This fixes OverdrawMode with circle layers.
While here, avoid using unique_ptrs for groups. Instead, ensure ElementGroup is movable.
Implemented observer callbacks so the style knows when the source’s attribution changes and the map knows when the style’s attribution changes. Also implemented a getter for a tile source’s attribution.
Fixes#2723.
This function can be called from different threads and was depending
on a global `std::string protocol` which can do heap allocations.
The first thread to use it would initialized it which is not exactly
safe, so this patch moves it to a `char *` that is just a pointer to
the data segment, so no races.
Valgrind detected it on #6431.
```
==9874== Conditional jump or move depends on uninitialised value(s)
==9874== at 0x4C307C2: __memcmp_sse4_1 (in /home/travis/build/mapbox/mapbox-gl-native/mason_packages/linux-x86_64/valgrind/latest/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==9874== by 0x79896E: mbgl::util::mapbox::isMapboxURL(std::string const&) (in /home/travis/build/mapbox/mapbox-gl-native/build/qt-linux-x86_64/Release/mbgl-test)
==9874== by 0x6DC756: mbgl::style::TileSourceImpl::parseTileJSON(std::string const&, std::string const&, mbgl::SourceType, unsigned short) (in /home/travis/build/mapbox/mapbox-gl-native/build/qt-linux-x86_64/Release/mbgl-test)
==9874== by 0x6DDA6A: std::_Function_handler<void (mbgl::Response), mbgl::style::TileSourceImpl::loadDescription(mbgl::FileSource&)::{lambda(mbgl::Response)#1}>::_M_invoke(std::_Any_data const&, mbgl::Response&&) (in /home/travis/build/mapbox/mapbox-gl-native/build/qt-linux-x86_64/Release/mbgl-test)
==9874== by 0x50BE80: std::_Function_handler<void (), mbgl::StubFileSource::StubFileSource()::{lambda()#1}>::_M_invoke(std::_Any_data const&) (in /home/travis/build/mapbox/mapbox-gl-native/build/qt-linux-x86_64/Release/mbgl-test)
==9874== by 0x70972A5: QMetaObject::activate(QObject*, int, int, void**) (in /usr/lib/x86_64-linux-gnu/libQt5Core.so.5.2.1)
==9874== by 0x70A3621: QTimer::timerEvent(QTimerEvent*) (in /usr/lib/x86_64-linux-gnu/libQt5Core.so.5.2.1)
==9874== by 0x7098053: QObject::event(QEvent*) (in /usr/lib/x86_64-linux-gnu/libQt5Core.so.5.2.1)
==9874== by 0x60CCC8B: QApplicationPrivate::notify_helper(QObject*, QEvent*) (in /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.2.1)
==9874== by 0x60D1E55: QApplication::notify(QObject*, QEvent*) (in /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5.2.1)
==9874== by 0x706FC2C: QCoreApplication::notifyInternal(QObject*, QEvent*) (in /usr/lib/x86_64-linux-gnu/libQt5Core.so.5.2.1)
==9874== by 0x70BC1AC: QTimerInfoList::activateTimers() (in /usr/lib/x86_64-linux-gnu/libQt5Core.so.5.2.1)
==9874==
```
* [core, ios, android] Use `auto` value for properties with calculated defaults
* Fix render tests
* [core] Don't use depth test unless text is pitch-aligned to map.
* Bump mapbox-gl-test-suite
* TransformState pitch is already in radians
* Reduce setDepthSublayer calls
* Bump test suite
