Handle latin1 (and other charsets)

files with latin1 (á é í...) characters/charsets don't work in doxia (non ascii chars are writted as ?). This souldn't be too dificult to implement: just set the charset to the writers:
The hard part is configuration.

A fixed example:

Index: src/main/java/org/codehaus/doxia/site/renderer/DefaultSiteRenderer.java
===================================================================
— src/main/java/org/codehaus/doxia/site/renderer/DefaultSiteRenderer.java (revision 135)
+++ src/main/java/org/codehaus/doxia/site/renderer/DefaultSiteRenderer.java (working copy)
@@ -264,7 +255,7 @@

RenderingContext renderingContext = new RenderingContext( moduleBasedir, doc, decorationModel );

• return new XhtmlSink( new FileWriter( outputFile ), renderingContext, directives );
  + return new XhtmlSink( new OutputStreamWriter( new FileOutputStream( outputFile), "ISO-8859" ), renderingContext, directives );
  }