Avoid segmentation fault for images with odd number of rows/cols
Set project to use tabs for new code to match existing main.m
Move main shrinking logic out of main()
Accept 1 to n command-line arguments to enable `ShrinkPng *@2x.png`
Merge pull request #1 from jlnr/master

Can now process multiple files at once. Fixed crash for images with odd number of rows/cols.