Rename chart as chart-send

Opens space for a chart-recv.
Add chart-recv command to read from topics
Fix views in server and render data as html page
Use a default x range when none is specified

Later it would be nice if the default were dynamically determined instead of
statically like this, but that requires out-of-band tracking.
Remove error implementation of unused VarcharColumn methods
Use first bucket as default range
Add reload templates option to chart-server
Fix chart-server help default for binding
Sketch out rendering of chart from /data