Don't clear overlay on mouseup if not zooming.

On endZoom, check if moveZoom was called since the last startZoom. If
not, leave the overlay canvas alone, there's no zoom rectangle to erase.

The default mouseup action unconditionally cleared the overlay canvas,
this destroyed other things that may have been drawn there such as
highlighted series, causing glitches for clickCallback use.
Add optional "locked" arg to setSelection

Locking a series selection temporarily disables the closest-series
logic of the highlighting code, switching it to traditional by-row
selection until unlocked by clearSelection().

This is useful for following values of a single series on mouseover,
see the example use in the "Highlight Closest Series" demo which
toggles this by clicking the graph.
Merge pull request #159 from klausw-g/lock-selection

Add optional "locked" arg to setSelection;  Don't clear overlay on mouseup if not zooming.
Two RangeSelector changes/fixes (pull request 160)
Merge branch 'master' of github.com:danvk/dygraphs
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
remove extra dygraph-combined link
declare vars in dashed-canvas
Fix missing object reference in interaction model.
Allow labelsDivWidth updates to be reflected in already-drawn graphs.
Merge pull request #162 from kberg/master

Two bug fixes that come from the recent push
Add option to many-points-benchmark that unaligns timestamps
Merge pull request #163 from flooey/master

Add unaligned timestamp option to benchmark
add crosshair demo back as per user request
tweaks to crosshair demo
remove trailing comma that was breaking IE
allow lint.sh to take a file as a command-line argument
fix all lint errors
 Merge branch 'master' of https://github.com/danvk/dygraphs
Stepplot and errorbars sync fix

The 1st error bar wasn't been drawn on stepplots, instead the script started with drawing the horizontal line of the 2nd error bar which was then shown under the 1st value, the 3rd error bar was drawn under the 2nd value, etc, what resulted in an incorrect graph.

Demo:

Without the fix:
http://wimme.net/temp/dygraphs1/index.htm
http://wimme.net/temp/dygraphs1/weather.htm
Notice how the error bars and the line charts are not in sync, the error bar is one value ahead

With the fix:
http://wimme.net/temp/dygraphs2/
http://wimme.net/temp/dygraphs2/weather.htm
Here are the error bars and the line charts nicely in sync, the way it should be.