* Add symbol dds attributes and adapt style code generation
* Update to mapbox-gl-js/master
* Refactor SymbolFeature as a subclass of GeometryTileFeature
Prepares for enabling DDS on symbol paint properties by allowing the
SymbolFeatures, which we keep around after constructing SymbolLayout,
to be used in evaluating data-driven paint properties later in the
layout process.
* Draft approach for splitting icon/text paint properties
The `Program` types are set up to bind GL attributes to each of the
data-driven paint properties specified in the `PaintProperties` type
provided. Since `SymbolPaintProperties` specifies both `Text*` and
`Icon*` properties, the symbolIcon, symbolIconSDF, and symbolGlyph
programs each attempt to bind roughly double the number of attributes
that they actually need.
This change addresses this by:
- Adding the more specific `IconPaintProperties` and `TextPaintProperties` types, which are subsets of the full `SymbolPaintProperties`.
- The symbol layer continues to use its `SymbolPaintProperties paint` member to track layer property state, but it provides helpers that construct objects of each the specific `{Icon,Text}PaintProperties::Evaluated` type, for use by the painter.
- The three symbol programs instantiate `Program<>` using the appropriate `{Icon,Text}PaintProperties` type.
* check in generated style code
* Populate paint buffers for symbol DDS properties
* Address first round of review comments
* Refactor VectorTile{Layer,Feature} to explicitly share data
* Update submodule
Provide Image::copy, which handles copying rectangles from a source to a destination, with thorough bounds checking.
Also fixes an indexing error in SpriteAtlas, where the top row of pixels in a wrapped image was copied from the wrong source row.
It should be safe to invoke GeometryTileWorker::setData multiple times without invoking GeometryTileWorker::setLayers. Therefore GeometryTileWorker::redoLayout() must not consume the layers.
ported from -js: eb6c6596c6a7a61363d30356674e0002153b1d19
`altitude` was a terribly-named variable that was used to indirectly
control the fov. This should eliminate some confusion.
`altitude` was equivalent to `cameraToCenterDistance / height`
