sampler class for lod, sampler is created and applied in lod objects
cursor label display set to inline-table, prevent wrapping at the right side

add multi-color hint for legend colorbox
add plotsampler.js to index.html
add lod switch in plotfactory, placeholder for lod line/bar/area
add lod js files to index
change the tip generation routine, now each rendering item can call applyAxis and get the tooltips

create a basic lod framework, add some implementation to lod line but there are bugs to fix
line lod implementation, 10k test passed
change the order of js in index
avoid shaking of lod lines, make consistent the lod tooltips based on zoom level

add lod hint message, add lod hint light (also for toggle lod type and disable)
auto box plot for lod line
display hint msg for lod, left click to switch lod type, right click to turn off lod, dispaly hint msg when lod is turned off
change the computation method to make the sampling stable, add time test (debug)
fix a bug that causes the sample tooltip to be unstable
make svg property names shorter
only create tip when resp is hovered (line done)
cleanup plotline
tip on-the-fly creation bar
bar cleanup
tip color generation for all items, area new tip creation method
tip on-the-fly creation for point, removing ele attr from prop generation