Updated readme for Spark changes.
Added subset support to demo app.
Merge branch 'master' of github.com:JosephCottam/AbstractRendering
Quadtree does segment proplerly.  Closes #2
Merge branch 'master' of github.com:JosephCottam/AbstractRendering
Removing 'known failing' test.
Fixes #14; status bar updates properly with parallel glyphs and quadtree
WIP: Turely parallel transfer (doesn't work yet).
Pixel-parallel transfer (marginally helpful).  Closes #3
Cascade panel renders, but recalculates base aggregates too often.
Pan works slow.
Pan works in pixel-locked step (a little slow)
Power-of-two zoom working (but still has a subsetting/TL only visible issue).
Adding 'test' build target (Closes #17)
Merge branch 'master' into UI
Avro schemas in ext jar (Closes #18)
Merge branch 'master' into UI
Cascade render works, but renders too often and presents too much blank space for transfer.
Misc cleanup and documentation.
Zoom and pan in cascade render much improved.