code style fixes:

- reordered includes to prevent accidental dependencies.
- moved arch specific files into their own folder (easier to include with cmake).
- renamed non-class files to reflect new code style (lower case with underscores).
- using full relative paths for includes (easier for understanding dependencies).
- using #pragma once instead of classic-style header guards.

src/test/integtests/platform/XWindowsScreenTests.cpp

@@ -16,10 +16,11 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <gtest/gtest.h>
-#include "CXWindowsScreen.h"
+#include "platform/XWindowsScreen.h"
 #include "synergy/CMockEventQueue.h"
 
+#include <gtest/gtest.h>
+
 using ::testing::_;
 
 TEST(CXWindowsScreenTests, fakeMouseMove_nonPrimary_getCursorPosValuesCorrect)