Review terminology in code/comments/docs in d7 version to reference image/styles/effects over imagecache/presets/actions

During the conversion from d6 to d7 the codebase was the priority over keeping the docs in-line with the terminology changes from d6 to d7.

For anyone who has worked with d6 this hopefully would be a non-issue in practice as the concepts of imagecache/presets/actions map to image/style/effects pretty much 1:1 but it could easily cause confusion for new developers and is all technically incorrect so the whole module needs a "once over" to clean this stuff up.