No argument to pnmcrop: cropping the top correctly.

Still leaves stuff on the left and the bottom.
Using the "-sides" argument: no visible cropping difference to no argument.
Using the "-white" pnmcrop argument: no difference in cropping to no argument.
Going back to no argument to pnmcrop.
Merge branch 'master' of https://github.com/steinarb/yr-cgi

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