Changes for 0.91.2

• For csv2rec, checkrows=0 is the new default indicating all rows will be checked for type inference
• A warning is issued when an image is drawn on log-scaled axes, since it will not log-scale the image data.
• Moved rec2gtk to matplotlib.toolkits.gtktools
• Moved rec2excel to matplotlib.toolkits.exceltools
• Removed, dead/experimental ExampleInfo, Namespace and Importer code from matplotlib