Autoscaling and limits in mplot3d.

    * Fixes improper setting of x,y,z limits not turning off autoscaling
    * Adds units support to z-axis
    * Adds shared axis support for z-axis
    * Closes #783
A bit of cleanup
Document that pcolormesh now takes a face argument to the edgecolor.
And clarify that the colorbar in axesgrid1 is also drawn with pcolormesh.
Merge pull request #1300 from jenshnielsen/pcolormesh_doc

Pcolormesh and colorbar documentation.
Update lib/mpl_toolkits/mplot3d/axes3d.py

Axes3D.scatter: raise exception in case z.size neither being 1 nor equaling x.size and y.size (according to documentation).
Update lib/mpl_toolkits/mplot3d/axes3d.py

Match argument names in error messages to argument names in documentation.
Update lib/mpl_toolkits/mplot3d/axes3d.py

Make Axes3D.scatter properly deal with `zs` being of size 1.
Use Objective C 1.0 [gs]etter
Merge pull request #1305 from dmcdougall/fix32bit

Fix pointer syntax error
Hide Tk root window until later

On Windows, when using the tkagg backend with mpl 1.2.0rc2, before a figure window is displayed, a small, empty window is shown for a short amount of time.
Fix circle marker -- it shouldn't be snapped because it contains bezier curves.
Use a snap threshold of 6.0 for the circle marker.
Merge pull request #1307 from mdboom/circle-marker-snap

Marker not round with markersize=3
Add documentation of colorbar issue #1188 to colorbar documentation
Merge pull request #1315 from jenshnielsen/colorbar_issuedoc

Add documentation of colorbar issue #1188 to colorbar documentation.
Fixes #1316.  Default to `None` for rasterization_zorder.
Cursor widget now uses widgetlock; closes Issue #156

While in the neighborhood, I did some minor reformatting.
Merge pull request #1320 from efiring/cursor_lock

Cursor widget now uses widgetlock; closes Issue #156
Fix tripcolor with shading='faceted'

In this case `edgecolors` is mistakenly set to a tuple `'k',` such that the following `ec.lower()` statement will fail with an `AttributeError`.
Merge pull request #1316 from mdboom/zorder-fix

very high negative zorder breaks vector graphic rendering