Comment reading/write improvements

This patch fixes some aspects of reading and writing comments:
- Multiple C++-style comments before a Json value had extra newlines appended to them. This patch removes the addition of those newlines.
- Comments written before Json values in the StyledWriter were not indented to match the indentation level of the value. This patch adds indentation to comments.
- Fixed inconsistency in newlines following C- and C++-style comments being saved as part of the comment. All newlines at the end of a comment are now removed.
- Added an additional test of comments.

https://sourceforge.net/p/jsoncpp/patches/25/

src/lib_json/json_writer.cpp

@@ -483,7 +483,20 @@ StyledWriter::writeCommentBeforeValue( const Value &root )
 {
    if ( !root.hasComment( commentBefore ) )
       return;
-   document_ += normalizeEOL( root.getComment( commentBefore ) );
+
+   document_ += "\n";
+   writeIndent();
+   std::string normalizedComment = normalizeEOL( root.getComment( commentBefore ) );
+   std::string::const_iterator iter = normalizedComment.begin();
+   while ( iter != normalizedComment.end() )
+   {
+      document_ += *iter;
+      if ( *iter == '\n' && *(iter+1) == '/' )
+         writeIndent();
+      ++iter;
+   }
+
+   // Comments are stripped of newlines, so add one here
    document_ += "\n";
 }