Fixed: AppKit unit-tests are not standalone

Previously, every AppKit tests used the same sharedApplication. Due to this implementation, a could not pass because a previous test made failed the current test. For instance, a test could fail because the window of the previous test resigned (just imagine a new window is the key window in the current test), and this resign could raise an error. The error was displayed for the current test thought this test was perfect !

We now instead of using sharedApplication create a new CPApplication per unit-test file in the class method setUp.

Tests/AppKit/CPTableViewTableColumnTest.j

@@ -1,13 +1,17 @@
 @import <AppKit/AppKit.j>
 
-[CPApplication sharedApplication];
-
 @implementation CPTableViewTableColumnTest : OJTestCase
 {
     CPWindow        theWindow;
     CPTableView     tableView;
 }
 
++ (void)setUp
+{
+    // This will init the global var CPApp which are used internally in the AppKit
+    [[CPApplication alloc] init];
+}
+
 - (void)setUp
 {
     // setup a reasonable table