Added python.tar zvm image for use with examples
c/echo: removed unneeded include
Added python 'echo' example
python/echo: Moved readme to the correct location
Added 'walk' sample
Added 'readwrite' python example
Added general README for workshop
Added 'custom lib' workshop sample
Added 'pngwrite' workshop sample
Added numbering to sample directories
Moved submodule for pngwrite workshop example
Added sequence number to pngwrite workshop sample
Added Python workshop README
Moved some workshop files to the correct place
Fixed pngcanvas submodule
Merge pull request #5 from larsbutler/python-workshop-2

Python workshop