cogl-atlas: Add some more debugging notes
cogl-atlas: Add some more debugging notes

This adds some debugging notes which report when the atlas is trying
various sizes.

djdeath/cogl,gcampax/cogl,gcampax/cogl,Distrotech/cogl,gcampax/cogl,djdeath/cogl,collects/cogl,djdeath/cogl,spatulasnout/cogl,djdeath/cogl-android,gcampax/cogl,Distrotech/cogl,Distrotech/cogl,Distrotech/cogl,collects/cogl,spatulasnout/cogl,djdeath/cogl-android,djdeath/cogl-android