using: Don't mess up alnums in indentifier-fontification.

Author: josteink

csharp-mode-tests.el

@@ -120,6 +120,9 @@
                         "using" 'font-lock-keyword-face
                         "Reference" 'font-lock-constant-face
                         "Under_scored" 'font-lock-constant-face
+                        "WithNumbers09.Ok" 'font-lock-constant-face
+                        ))
+
                         ))
 
 (defun list-repeat-once (mylist)

csharp-mode.el

@@ -762,11 +762,11 @@ to work properly with code that includes attributes."
            ,`(,(concat
                 "\\<\\(using\\)[ \t\n\f\v\r]+"
                 "\\(?:"
-                "\\([A-Za-z_]+\\)"
+                "\\([A-Za-z0-9_]+\\)"
                 "[ \t\n\f\v\r]*="
                 "[ \t\n\f\v\r]*"
                 "\\)?"
-                "\\(\\(?:[A-Za-z_]+\\.\\)*[A-Za-z_]+\\)"
+                "\\(\\(?:[A-Za-z0-9_]+\\.\\)*[A-Za-z_]+\\)"
                 "[ \t\n\f\v\r]*;")
               (2 font-lock-constant-face t t)
               (3 font-lock-constant-face))

test-files/using-fontification.cs

@@ -1,2 +1,3 @@
 using Reference;
 using Under_scored;
+using WithNumbers09.Ok;