Use space in comments in webp

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

As desired by #112.
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.
Merge pull request #201 from ruud-v-a/whitespace

Use space after // and ///