This significantly improves performance, since we already create the
elements when measuring them, and that effort is now no longer wasted.
We must take care to detach, rather than remove, when clearing the text
layer, so we can add the elements back later if necessary.

Since the Canvas .text object is jQuery-wrapped, it was not preserved as
expected when clearing the canvas of junk.  I've replaced the selection
with one based on element classes.

Instead of giving the axis its own font property, we simply look at its
options, where the font comes from in the first place.  A separate
property is unnecessary and inconsistent with the way other axis options
are handled.

The base implementation uses the new drawText and getTextInfo methods to
draw text in HTML.  Canvas rendering has been moved to overrides of
these methods within the canvas-render plugin.

These methods provide a common way to draw HTML text above a canvas.

The getTextInfo method generates div HTML for text with a given font
style/class and angle, measures the element's dimensions, and saves
everything in a cache.  The drawText method takes the resulting entry,
finishes generating the inline styles necessary to position the div, and
adds the result to a buffer.  The render method dumps the buffer into an
overlay and expires unused cache entries.

Moved canvas creation and size management into a new Canvas class.

This is the first step towards a more object-oriented architecture.
Since we create multiple canvases, and have to maintain several
module-global variables to track their properties, they are the ideal
place to start.

This commit also removes sizing code that was duplicated between
makeCanvas and resizeCanvas.

Renaming the variable gives us room to create a new class called Canvas.

Fix an error in plot offset calculation.

Correction calculation error margin 

Ensure that tickSize updates on subsequent calls to setupGrid.

Fixed jQuery version dependency (we require 1.2.6, not 1.3.2) and
whitespace.

Flot's semver is 0.8.0-alpha, and it (for now) requires jQuery 1.2.6,
not 1.3.2.

Adding component.json for bower.

Added a series 'zero' option to control automatic scaling.

Adapted from pull request #17.

Always draw crosshair on half-pixels to prevent aliasing.

Add passing offsets over plotpan event

Due to limitations in our plugin architecture, the categories plugin
duplicates code from Flot's core for adding a dummy point to snap the y
axis to zero.  We can get rid of this duplication in 0.9; for now we'll
just update the duplicate to match the change in core that introduced
the new 'zero' option.

This also includes a tweak to zero's default.  Previously zero only
received a value if lines were visible; now it always receives a value,
matching the behavior of other contextual options.

Unified this behavior with plotzoom event as in pull #34 flot/flot@1b6c4e933ade3f03d634dfaa6357e82beda3bc55

Use bind, rather than .mouseleave, because we officially still support
jQuery 1.2.6, which doesn't define a shortcut for mouseenter or
mouseleave.  This was a bug/oversight that was fixed somewhere around
1.3.x.  We can return to using .mouseleave when we drop support for
1.2.6.

Change evaluation order for calculating percentage.

Rounding errors are introduced when calculating the percentage when the total is 100 (for example if percentages have already been calculated). Calculating (total/100) first eliminates the error in this case.

Added a format option 'autoscale' that controls whether the given point
is considered when determining an automatic scale.

The lines & bars 'zero' option controls whether autoscale is set on the
dummy point that is inserted to create the series lower-bound.

Area and bar plots normally use a minimum of zero, since their purpose
is to show size, and using an auto-scaled minimum distorts the plot's
meaning.  But this behavior is undesirable in cases where the plot type
is used in more of a decorative sense.

The zero option provides a way to control this behavior.  It defauls to
true for bars and filled lines.

When the placeholder has (or inherits) the HTML 'dir' attribute or CSS
'direction' we get unexpected results from text metrics, resulting in
visual glitches on the axes.

The suggested solution in #716 was to set ltr on the placeholder, but
this introduces its own problems, since the user probably *does* expect
rtl on items like the legend.  So we'll instead set ltr only on the
canvases.

We should review this behavior at some point; rtl is something we need
to handle, not work around.  It also needs to be kept in mind as we move
canvas-text into a plugin.  But for now this solution at least ensures
consistent behavior.

As pointed out in a comment to #832, initializing maxIndex to zero
results in the creation of a single color even when all indexes are
fixed.

Allow the pie chart to redraw on resize or update.