Instantiate barLeft/barRight in Bar Highlighting Section

The autoscale check was too broad; it included the case where autoscale
was undefined.  This resulted in axes not expanding correctly when
coordinates at the end of a series had null x or y values.  Fixed by
narrowing the check to !== false; resolves #1095.

The drawBar method was always called with an offset of zero, and I see
no other way in which it is currently used. Resolves #382.

This is up to 2x faster and appears to work around issues in Chrome's
canvas implementation that sometimes result in bars not being filled.
Resolves #915.

Fixing Issue 686: Tooltip bug

Resolves #997 and #1081.

Throwing an exception was overkill for such a limited-use option; we
should reserve those, and the file-size bytes they consume, for serious
cases only.

Support for right-aligned bars was never added to the hover or highlight
code; only the actual bar drawing. We need to replicate that in the
other two places as well.

Resolves #1093.

Always remove the tick text in drawAxisLabels() regardless of axis settings

Since a plot may be redrawn after removing ticks or hiding the axis,
the tick text should always be removed before determining if there are
ticks to draw.

Fix typo in API.md

Change [olson] to http link

GitHub doesn't render ftp links for some reason ([security?][1]).

[1]: https://github.com/mojombo/jekyll/issues/373#issuecomment-15025728

Add table of contents

The reference document is quite large; a table of contents would help readers navigate and find topics. (TOC was generated via [DocToc](http://doctoc.herokuapp.com/))

Lots of people ask about implementing tooltips; hopefully enabling it by
default will help them find it more easily.

These changes were used to test the axis innermost property fix, and
should not have been committed.

An axis is innermost when it's first among those not just in its
direction, but also on its side, i.e. left/right, of the plot. So the
inArray check should be against the samePosition list, not all.
Resolves #1056.

It doesn't make sense to calculate the innermost property only when no
tickLength has been provided; the two have little to do with each other.

Resolves #1032.  Previously it was impossible to draw the same text,
with the same style, in two different locations, because the second
would end up using the first's cache entry, which only ended up moving
the element to a new position.

Now each cache entry holds a list of positions at which the text
appears, creating clones of the original element for each position
beyond the first.

Resolves #1030.  The performance impact should be low, and is the
correct thing to do in just about all cases where a plot is being
redrawn.

Resolves #1033.

 Removed executable permissions from jquery.flot.selection.js

Flot 0.7 calculated x-axis label dimensions by assigning each label a
fixed width, then measuring the height as determined by the browser.  A
side-effect of this technique is that x-axis label divs received a fixed
width.  The rewrite of the text system in 0.8 accidentally removed this
feature; this patch restores it.