Switch funnel to use SVG

Fix multiseries scalar/funnels. 

Fixup the pg tests to run only when the postgres engine is enabled

crate jdbc: version bump to 2.1.6

Clarify funnel documentation

Improve visualization docs

Catch and surface Pulse channel errors

* commit filter on enter

* fix context issue

* use key instead of keycode

* properly bind function

Support multiple filter values using comma separation instead of multiple input fields

Use kmeans to automatically group map data

* update icons and remove old illustrations

* fix icon string

* fix icon path

See http://roadtolarissa.com/coloring-maps/ and
http://bl.ocks.org/thadk/37ff4c03358b414acd1e as to why this is a better
solution than quantize.

bump version number to 0.24-snapshot

Merge release 0.23.0 back in

Make sure to de-CLOB-er the error message for H2 legacy query executions