Various improvements

The attached patch addresses the following issues in inline.module:

• You can now specify [inline:filename.ext] instead of only the number, for added link stability.
• A bold, red NOT FOUND message is shown if the given file name or number does not exist.
• The module previously generated spaces around the img and a tags. Those are gone.
• Images are only inlined if linked to with [inline:...]. If you say [file:my.png], this will remain a file link.
• The recent fix for multiple links in one node is part of this patch.