Adds arguments to the plotzoom event and fixes the bug where zooming could overrun a plot's pan range.

While Flot's codebase is currently a mish-mash of styles, we'd like to
move toward a unified style based on the jQuery core style guidelines.
Migration of existing code is scheduled for the 0.9 release.

Fix setting border color/width as an object.

* If either color or width is object, normalize the other to object
* Only draw each border if its width is greater than 0
* Set strokeStyle and lineWidth _before_ calling ctx.beginPath()

Return null from getSelection if there's no selection.

Fixed pie plugin 100% slice issues on IE7/8.

When a slice equals (or comes close enough that it is equal in
floating-point representation) 100% of the pie, it was no longer drawn
by Excanvas.  This is because of a long-standing issue where VML won't
draw an arc whose begin and end are the same.  Rather than some hack,
like adding/subtracting a small value, we'll simply draw two arcs for
every slice, with each covering half of the slice's angle.

Fix tickDecimals option broken by pull #50.

Pull request #50 inadvertently broke the behavior of axis.tickDecimals,
which previously added precision up to the given value.  The broken code
effectively ignored the setting for values with less precision.  This
fix brings back the old behavior.

It's useful to include the tickDecimals option in one of our examples,
so it's easier to test across versions.  The setting-options example is
the logical place to put it.

Tested, verified and fixed support for jQuery 1.8.

Substitute zero when .width() returns undefined, since legendWidth is
used in numeric calculations that break when it is undefined.  This
became a problem with the release of jQuery 1.8.0, which returns
undefined instead of null when an element doesn't exist.  This was fixed
in 1.8.1, but this is good practice anyway.

Use placeholder dimensions instead og canvas dimensions in calculations which fixes draw bug after introducing Retina support in Flot core

Removed implicit global variables in threshold plugin.

Cleaner and portable function to get pixelratio.