tighten up fix for {{.}}

realizing previous commit would treat {{.foo}} the same as {{.}}

src/main/java/com/samskivert/mustache/Template.java

@@ -81,7 +81,7 @@ public class Template
             // if we're dealing with a compound key, resolve each component and use the result to
             // resolve the subsequent component and so forth
              
-            if (name.indexOf(DOT_NAME) > 0) {
+            if (name.indexOf(DOT_NAME) > 0 && !DOT_NAME.equals(name)) {
                 String[] comps = name.split("\\.");
                 // we want to allow the first component of a compound key to be located in a parent
                 // context, but once we're selecting sub-components, they must only be resolved in the