docs: added come FAQ entries
agglite driver: added support for stroke-width units.
PolygonizeLines: added shader-based scaling control.
agglite: Fix wgs84 case, enforce minimum pixel width
stroke-min-pixels support, added to symbology ref docs as well
agglite: fix support for pixel widths
Style: made text/css optional as long as there is content in the text value of the Config
MAJOR UPDATE: reworked the shader composition framework with new VERTEX and FRAGMENT locations. VERTEX shader functions now require an inout vec4.
Docs: updated the shader composition docs to match the new shader comp setup.
TraverslaData: fixed incorrect identity matrix type assignment on mat3 uniform
MapNode: fix possible NULL pointer dereference. #297
GLSL: fixes for iOS under new shader comp fx
Add byo engine files
Corrections and improvements to "Sampling Image Layers" section.
Merge pull request #299 from XenonofArcticus/master

Sampling Image Layers doc fix.
Calling isLayerValid on ElevationLayerVector::createHeightField.
Merge branch 'master' of github.com:gwaldron/osgearth
CURL: added global curl initialization to the Registry ctor since it's not thread safe
Merge branch 'master' of github.com:gwaldron/osgearth
CURL: moved the global_init into a static HTTPClient function instead