Custom display/theming

This is an offshoot of http://drupal.org/node/59209.

Cause:
The current way of setting image size and alignment is too customizable and requires too much knowledge from users respectively.

Goal:
Users are in the need of placing images with pre-defined styles into their contents.

Usage example:

• Inlining images of team members with a pre-defined style (f.e. black border right and below) and align.
• Inlining screenshots with a pre-defined size and align.

Details:

• There is no obvious approach to accomplish this, since we have two specifications (image size and image alignment), which would have to become one: image style.
• Less experienced users do not have to complain about design decisions, they just choose the corresponding image style based on the question "what is this image?".
• However, more experienced users still have to be able to override those image styles by choosing a custom image size and image align.

Procedure Approach:

• Admin should be able to additionally define image styles in settings, each with style name and image size.
• In img_assist dialogues, users choose from a list of image styles first, if some are set up.
• There is a default entry in the list of image styles "other". Choosing this option will let appear the (current) image size and image align select boxes in the form.
• If no image styles exist, the (current) image size and image align select boxes are displayed instead of the image style select by default.
• img_assist places images inlined with a image style with their image style as CSS, f.e. style="inline imgstylename". Site admin/designer is able to set up custom styles for these classes.
• img_assist dynamically creates a theme_ function for each chosen image style to allow override of image output in theme.