changed double to single quotes in 01-intro
changed single to double quotes in 02-reuse
fixed analyze.m to generate a neater subplot
Added plots to 02-loop
Removed class out from img divs in 01-intro
small fix to make_heatmap
added images used in lessons 2 and 4
added images to lesson 4 and a few small fixes
fixed a bug in call to min function
set 'axis equal' for colormaps, removed TODO: section on colormaps
Merge pull request #787 from ashwinsrnth/add-images-to-matlab

Adding missing images to the MATLAB lessons. Also added consistency in the way we represent strings - all single quotes.