Replace backticks with repr() or "%r"

From SF patch #852334.
diff --git a/Lib/plat-mac/FrameWork.py b/Lib/plat-mac/FrameWork.py
index 849ebdf..7242704 100644
--- a/Lib/plat-mac/FrameWork.py
+++ b/Lib/plat-mac/FrameWork.py
@@ -373,7 +373,7 @@
             # else it wasn't for us, sigh...
 
     def do_char(self, c, event):
-        if DEBUG: print "Character", `c`
+        if DEBUG: print "Character", repr(c)
 
     def do_updateEvt(self, event):
         (what, message, when, where, modifiers) = event
@@ -431,13 +431,13 @@
 
     def printevent(self, event):
         (what, message, when, where, modifiers) = event
-        nicewhat = `what`
+        nicewhat = repr(what)
         if eventname.has_key(what):
             nicewhat = eventname[what]
         print nicewhat,
         if what == kHighLevelEvent:
             h, v = where
-            print `ostypecode(message)`, hex(when), `ostypecode(h | (v<<16))`,
+            print repr(ostypecode(message)), hex(when), repr(ostypecode(h | (v<<16))),
         else:
             print hex(message), hex(when), where,
         print hex(modifiers)