Replace usage of Character.isAlphabetic with Character.isLetter
Revert "Move the renderer link stuff into its own package"

Sadly needed for backwards compatibility

This reverts commit d964410ffcd40b3ebf420595ff4163b292082478.

Conflicts:
	src/net/hillsdon/reviki/wiki/renderer/creole/CreoleASTBuilder.java
	src/net/hillsdon/reviki/wiki/renderer/creole/ast/Image.java
	src/net/hillsdon/reviki/wiki/renderer/creole/ast/Link.java
Fix test broken by the top-level result node type not being an interface any more
Update rendering extension tests
Remove tests for detecting outgoing links in HTML: it's now done through the AST
Implement anchor tags