STY: use .get instead of a try/except

Author: wasade

src/screenControl.py

@@ -511,8 +511,4 @@ def moveCursor(self):
 
     def getKey(self):
         charCode = self.stdscr.getch()
-        try:
-            char = mapping[charCode]
-        except KeyError:
-            return ''
-        return char
+        return mapping.get(charCode, '')