Tight layout function


Thanks for the newly added plt.tight_layout function to the master mpl branch. This saves me from manually adjusting the spacing around the figure canvas each time I need to use the full available figure space. For this I was switching from Qt4Agg to WXAgg backend, so that I was able to read right/left/top/bottom/hspace/wspace parameters numerically and then feed into plt.subplot_adjust function. I guess there is no need for this long path with the addition of this new adjuster function.