Test and linted
table header moved to dc.js

Still allows original example to function as-is.
Allows non-hard-coded table column headers.
Exposing filter functions for easier overrides
changed data-table to support dynamically set columns for table header

Supplied 3 examples of setting the columns; the original method, which
requires the fixed html code for thead/cols; another which uses mostly
the data element names which become capitalized as col headings, and
another where most of the columns have the column label specified along
with an accessor function. There is some code to strip a
numberFormat/etc from a function converted to string, an attempt to
auto-generate a column header from a function, in data-table.js,
columnString().
fixing unintended checkins
updated stock example via grunt
attempt again, renderedstockfixture
attempt3 after installing saucelab; touched data-table.js
retry 4. connected sauce
Merge branch 'master' into expose_filter_functions
review changes

Restored index.html, no need for a change.
Added 4th example of columns.
updated restored stock example
added ValueFormat function

so both header and value can be overridden
Removed columnHelper fn

Changed to use just an in-line Object, and allow any Object
specification desired, with note to override the internal functions to
match.
I think this is the cleanest and most flexible version.
Revert "Exposing filter functions for easier overrides"

This reverts commit baa154e28be4f760f28b07881b2409666ff17872.
Merge branch 'master' into expose_filter_functions
Changes to reflect Gordon's proposal for exposing chart filtering
Added hasFilterHandler.  Added code documentation
Fixes column and row text after the heatmap has been filtered.  This includes transitions for column text and removal of both column/row text on exit
Adds test for heatmap bug.  Still passes on master because the transitions don't load the new text right away.  Possibly need a wait?