Use space in comments in webp

As desired by #112.
Use space in comments in png

As desired by #112. This also removes old code that was commented out.
There was more of that kind of code, but somebody more familiar with the
codebase should take a look at that.
Use space in comments in imageops

As desired by #112.
Use space in comments in gif

As desired by #112.
Use space in comments in jpeg

As desired by #112.
Use space in comments

This fixes #112. This also removes a line of old code that was commented out.