Change Zenburn caret colour to white

Also improve colours for brace_good/bad and indent guide.

colorschemes/zenburn.conf

@@ -23,13 +23,13 @@ error=#e37170;#332323
 
 selection=#000;#7d7d7d;false;true
 current_line=#000;#636363;true
-brace_good=#00f;#fff;true;false
-brace_bad=#f00;#fff;true;false
+brace_good=#dcdccc;#7d7d7d;true;false
+brace_bad=#e37170;#7d7d7d;true;false
 margin_line_number=#7f8f8f;#464646
 margin_folding=#7f8f8f;#4c4c4c
 fold_symbol_highlight=#464646
-indent_guide=#c0c0c0
-caret=#000;#000;false
+indent_guide=#666
+caret=#fff;;false
 marker_line=#000;#ff0
 marker_search=#000;#0000f0
 marker_mark=#000;#b8f4b8