Rename wxTextFieldCell members once again

Use underscores on them to show that they are different from properties or
local variables (in pure Objective C they would actually start with
underscores, but this is not a good idea in C++ code) and avoid conflict
between a member name and "wxAlignment" type name, which was confusing.

include/wx/osx/cocoa/dataview.h

@@ -378,8 +378,8 @@ private:
 @interface wxTextFieldCell : NSTextFieldCell
 {
 @private
-    int wxAlignment;
-    BOOL adjustRect;
+    int alignment_;
+    BOOL adjustRect_;
 }
 
     -(void) setWXAlignment:(int)alignment;