gradle: update jeo repo url
refactor: move compileVertexItems() to RenderElement

- rename addPoolItems -> compileVertexItems
add IndexedRenderElement
let MeshLayer extend IndexedRenderElement
use common vertexItems field in ExtrusionLayer
add HairlineLayer
PolygonLayer: separate drawing of stencil clip region
PolygonLayer: cleanups
wip: use HairLine for PolygonLayer outlines
MapRenderer: increase shared quad vertices
renderer: cleanups
VertexData: docs

- remove superfluous static get()
MapRenderer: refactor native buffer utils
PolygonLayer optimizations:

- check of polygon elements are visible
- use AreaStyle.hasAlpha() to enable blending
- GLState.testDepth()
- LineClipper: add outcode(x,y)
GeometryBuffer:

- add getPoint(i, point)
- addPoint(PointF)
- getPointX/Y

GeomBuffer: api
GeometryBuffer: switch to int[] indices
add ElementLayer/RenderElement prepare()

- used to prepare for compile() when all layer data is added
RenderElement: docs
jni: add GLMatrix proj2d/3d
jni: new Tesselator