Add 'plotter' option, which allows custom drawing.

Add 'plotter' option, which allows custom drawing.

This can be used to create bar charts, mixed bar/line charts, box and whisker
charts, chandle charts, or whatever you can dream up.

Squashed commit of the following:

commit 0d5ce69dda5f02db7a4576b220f8cb7bc45cd197
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Tue Jul 31 12:38:43 2012 -0400

    bug fix

commit 15e29ef96fc41e73512edf7c404462cfa6f7ed3c
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Tue Jul 31 12:37:21 2012 -0400

    kberg comments

commit 0a61073b21bb92002f9808356be02e015b584450
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Tue Jul 31 11:04:49 2012 -0400

    copy over more stuff in push-to-web

commit 3b9f9d1b6ca68a61d593ff909f2cdab2827b3410
Merge: 7f808fd 85e975f
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Tue Jul 31 10:49:06 2012 -0400

    Merge branch 'master' into plotter-option

commit 7f808fd2944d486d567a07768c1849aad1cb2768
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Tue Jul 31 10:28:19 2012 -0400

    mixed error/line

commit 5b5d1c37504749fd35ab1d862bcfc871a99ba422
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Mon Jul 30 21:28:04 2012 -0400

    tweaks to plotters demo

commit 371163baa1086f99e126a5896acb09a535c019c2
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Mon Jul 30 21:27:50 2012 -0400

    Dygraph.Plotters

commit 6446f7c315a7f58e9daa39a2c1cbd2c877ae7870
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Mon Jul 30 21:08:49 2012 -0400

    a few more plotter examples

commit 7867dbdf2b4733de76d3ed8d999336ba58ccba86
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Mon Jul 30 18:55:02 2012 -0400

    cleanup & comment

commit d8768ade1b85c81af5df52b7425f870f420babfc
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Sun Jul 29 20:08:01 2012 -0400

    fix highlightSeriesOpts issue

commit bfbf2452e7f34088de46242c5bf54e3904c6a49d
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Sun Jul 29 19:47:20 2012 -0400

    more cleanup

commit f8fdb6b618443b2a74ce5861f2aa0ce1206320e3
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Sun Jul 29 19:43:43 2012 -0400

    reduce number of params to various line drawing function

commit 2d101ef9d34a9a52a7051cc2698f12f435854a04
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Sun Jul 29 19:25:15 2012 -0400

    only use fillPlotter when necessary

commit 0a7c6dca3e21261874b6c88c02c626e9c5f5cad9
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Sun Jul 29 19:22:32 2012 -0400

    fix issue with fillPlotter & visibility

commit fb86aa8b43bd02f594ea3c05840d0d40d965b1be
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Sat Jul 28 19:10:24 2012 -0400

    restructure, comments

commit c77fe2f37e60d394d1cffaf1126955d014b44838
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Sat Jul 28 17:52:52 2012 -0400

    port over fillGraph plotter

commit 04b5eb3b52be9f2c12f959378f8ae35c22008ded
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Sat Jul 28 17:44:58 2012 -0400

    add candle chart demo

commit 27737ae38eac6b6096687d8960f8b34fd4ec8dfa
Merge: b81d3fc 6f8f19e
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Wed Jul 25 17:49:37 2012 -0400

    Merge branch 'master' into plotter-option

commit b81d3fcbceaa115d16710a328747b8a7b2af9788
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Wed Jul 25 17:47:27 2012 -0400

    pass all series plus seriesIndex to plotters

commit 727229cbe532d2088f59d886ab368df4d499d5d8
Merge: fd784bf 16879a6
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Wed Jul 25 17:43:51 2012 -0400

    merge upstream changes

commit fd784bf9c0d18173238c921a4fde8fc35946b9c0
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Tue Jul 24 19:50:02 2012 -0400

    drawXgrid

commit b638898ad332edc71ed26528604eab94bcc791be
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Sat Jul 21 20:29:51 2012 -0400

    Bar chart plotter demo

commit 0eeb143cb02d29e38bda87a273be737c7623686e
Author: Dan Vanderkam <dan@dygraphs.com>
Date:   Sat Jul 21 20:06:51 2012 -0400

    add line & error plotters; highlightSeriesOpts is broken