Correctly handle screen rotation on iOS
first step
Merge branch 'master' into lifecycle
dynamic polyline
Add some helper functions for the UVs
fixing uv on polygons
Merge branch 'master' into multiStyles

Conflicts:
	core/src/style/style.cpp
Makes Android Tangram class a modular view that is simple to add to an Activity; Tangram now extends View and acts as its own Renderer and GestureListener
Ask Android to preserve GL context on pause, preventing crashes from invalidated GL resources; We'll need a fallback for when this can't be satisfied, but for now this solves GL-related crashes on all tested devices
Prevent TileManager from trying to get data from a tile that failed to load
Add a mutex member to DataSource and lock it when modifying the tileStore concurrently
Merge branch 'master' into lifecycle

Conflicts:
	android/src/com/mapzen/tangram/MainActivity.java
Allow Android app to rotate screen without re-creating Activity
Modify View to handle screen rotation more consistently; View now stores the current screen dimensions and scales itself such that tiles are 256 x 256 px in screen space (at their base)
Misc Changes (Described further)

1. Added debug flags to ios cmake
2. pan velocity takes zoom level into account now, fixes the inconsistent pan speed when at different zoom levels.
3. added some checks in View::setZoom to better handle valid tile IDs
Fix zoom value clamping
Merge branch 'master' of https://github.com/tangram-map/tangram-es
Prevent re-instantiation of top-level tangram members
Track ShaderPrograms in a static list\n\nEnables rebuilding shaders after GL context loss
adding core base files for raspberry Pi