First cut of scene::data family and first unit test for it.  Also changed geomData::Indices to be a typedef to std::vector rather than a trivial derived class from std::vector.  Hoisted a couple general things from sprite to geomFx.
Implemented migrate (change element bindings and realloc without losing current values) for scene::data.  Other small cleanups to scene::data too.
Cleaned up scene::data and scene::lines.  Added pnipstd.h for std::hash specialization for std::pair.
Added iterators to scene::data class.  So much nicer.  Scaffolding in place for generating line geometry in scene::lines.
Drawing a line!  Lots to do still to make it good.  Also cleaned up scene::data... much closer to good now with proper iterator deref operators.
Added viewport size to the builtin uniforms.
Working screen-space line thickness with /some/ compensation for non-square pixels.  A number of todos to go, but checkpointing progress.
Added scene::dirty to embody the pattern of having dirty data that is cleaned up lazily.  Made scene::lines class absolutely tiny.  Will need to propagate this to other places.
Implemented invalidate and cleanup of bounds for scene::lines.  Small tweaks to scene::dirty to include setDirty callback function.
Implemented much more efficient line -> geom generation.  One step away from doing better miters, too.
Improved scene::lines miter calc on cpu side.  Now need to add uniforms to handle non-square pixel framebuffer targets (e.g., a texture framebuffer that will be stretched vertically to match output resolution)
Whew... figured out problem with new line extrusion in ndc was a missing normalize before adding the tangent (a_normal) to the src point.  Sigh... not totally sure why that caused a range problem though.
Uniform for scene::lines vs is working to scale for anisotropic framebuffers.
Refined scene::lines.  Added interactive line drawing to test app.  Lines are pretty stable, but expected artifacts for sharp edges do show up.  Next is filling out the fs for lines to do antialiasing.
WIP on antialising scene::lines.  Working nicely... hardcoded a dashed line right now.  Will promote a number of things to uniforms next.
Added lines::style and transitioned all hacks in lines fs to use uniforms from lines::style.  Animated dashes are pretty cool.
Lots of cleanup... building up better lines example... just noticed lines copy constructor sucks because of closures capturing and propagating the wrong this ptr to new copies.  Working on a fix for that.  Changed fs for lines to use triangle wave for dash edges rather than sin wave.  Updated dup operators in scene to leverage covariant return types.
Better demo of lines running now, with a range of sizes and styles.
Cleaned up lambda references in some areas... needed to convert a bunch to copies for async use.