SciTools/iris — pull request #204 by esc24 (2012-11-15 15:43:08+00:00)
Title: Implicit out of place guess_bounds when using pcolor and pcolormesh

Having loaded a cube it is extremely useful to be able to quickly visualise the data using pcolormesh. If the cube's coords don't have bounds the user must figure out the name of the coords. They then have to call ```guess_bounds()``` on those coords. This is not trivial and requires the user to inspect and modify the cube before they have seen the data. I propose that ```iris.plot.pcolor()``` (and ```iris.plot.pcolormesh()```) guess the bounds if they do not exist (issuing a warning) and plots the result leaving the cube untouched.