Remove trailing whitespaces

Many tools strip trailing whitespaces by default, so after editing a file with
whitespace errors we end up with a bunch of unrelated hunks that need to be
reverted locally.

This could be fixed by configuring each tool to not do this (at least for the
barrier repo), or, simpler, we just sed the problem away and make barrier
whitespace-compliant.

sed commands run:
    sed -i 's/[ \t]\+$//' **/*.(cpp|h) **/*CMakeLists.txt

Verified with git diff --ignore-space-change, this shows the empty diff.

src/lib/client/Client.cpp

@@ -2,11 +2,11 @@
  * barrier -- mouse and keyboard sharing utility
  * Copyright (C) 2012-2016 Symless Ltd.
  * Copyright (C) 2002 Chris Schoeneman
- * 
+ *
  * This package is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * found in the file LICENSE that should have accompanied this file.
- * 
+ *
  * This package is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
@@ -134,11 +134,11 @@ Client::connect()
         // being shuttled between various networks).  patch by Brent
         // Priddy.
         m_serverAddress.resolve();
-        
+
         // m_serverAddress will be null if the hostname address is not reolved
         if (m_serverAddress.getAddress() != NULL) {
           // to help users troubleshoot, show server host name (issue: 60)
-          LOG((CLOG_NOTE "connecting to '%s': %s:%i", 
+          LOG((CLOG_NOTE "connecting to '%s': %s:%i",
           m_serverAddress.getHostname().c_str(),
           ARCH->addrToString(m_serverAddress.getAddress()).c_str(),
           m_serverAddress.getPort()));
@@ -255,7 +255,7 @@ Client::leave()
     m_active = false;
 
     m_screen->leave();
-    
+
     if (m_enableClipboard) {
         // send clipboards that we own and that have changed
         for (ClipboardID id = 0; id < kClipboardEnd; ++id) {
@@ -775,7 +775,7 @@ Client::writeToDropDirThread(void*)
     while (m_screen->isFakeDraggingStarted()) {
         ARCH->sleep(.1f);
     }
-    
+
     DropHelper::writeToDir(m_screen->getDropTarget(), m_dragFileList,
                     m_receivedFileData);
 }
@@ -790,7 +790,7 @@ Client::dragInfoReceived(UInt32 fileNum, std::string data)
     }
 
     DragInformation::parseDragInfo(m_dragFileList, fileNum, data);
-    
+
     m_screen->startDraggingFiles(m_dragFileList);
 }
 
@@ -806,7 +806,7 @@ Client::sendFileToServer(const char* filename)
     if (m_sendFileThread != NULL) {
         StreamChunker::interruptFile();
     }
-    
+
     m_sendFileThread = new Thread(
         new TMethodJob<Client>(
             this, &Client::sendFileThread,