Fix typos in docs and comments

Doc/Manual/Doxygen.html

@@ -181,7 +181,7 @@ or enum element comments:
 <div class="code"><pre>
 enum E_NUMBERS
 {
-    EN_ZERO, ///&lt; The first enum item, gets zero as it's value
+    EN_ZERO, ///&lt; The first enum item, gets zero as its value
     EN_ONE, ///&lt; The second, EN_ONE=1
     EN_THREE
 };