Simplify names and structure;

SceneDirector folder and class removed, functionality moved to Tangram.cpp;
dataSource folder renamed to data;
sceneDefinition folder and class renamed to scene;
mapTile moved to tile folder;
tileManager moved to tile folder;
ViewModule folder and class renamed to view;
Tangram namespace added to tangram.h and tangram.cpp
Add platform client code to use Tangram namespace and call update() using correct timestep
Rename projection.h to mapProjection.h to match class name
Extract OpenGL headers from platform.h and move into gl.h
Merge branch 'master' into reorg

Conflicts:
	android/jni/jniExports.cpp
	android/jni/platform_android.cpp
	android/src/com/mapzen/tangram/TangramRenderer.java
	core/src/platform.h
	ios/src/platform_ios.cpp
	osx/src/platform_osx.cpp
Post merge from master branch:
    Added platform.h to have a reference of setAssetManager
Git loves new lines
Merge branch 'reorg'