Created std.ascii to replace std.ctype.

All of the new, properly camelcased functions in std.ctype have been
moved to std.ascii, and std.ctype has been scheduled for deprecation.

std/uri.d

@@ -30,7 +30,7 @@ module std.uri;
 
 /* ====================== URI Functions ================ */
 
-private import std.ctype;
+private import std.ascii;
 private import std.c.stdlib;
 private import std.utf;
 private import std.stdio;