Add Regular Expression support to editor search & replace

The "3. Editor Find & Replace" feature added to Confluence 4.1 could really use the addition of (optional) support for regular expressions in the "find" term, and back-references in the "replace" term.

Similar support is available in JSPWiki, and allows complex search/replace to be done on pages.

Example:

Make all bullet list entries bold:

Find (regex): ^(* )(.+)
Replace: \1*\2*

(assumes backreferences to capturing groups are made using backslash, JSPWiki uses "$")

A screenshot using the above example, using JSPWiki, is attached to this issue