Remove trailing whitespace from most CMake and C/C++ code

Our Git commit hooks disallow modification or addition of lines with
trailing whitespace.  Wipe out all remnants of trailing whitespace
everywhere except third-party code.

Run the following shell code:

git ls-files -z -- \
 bootstrap doxygen.config '*.readme' \
 '*.c' '*.cmake' '*.cpp' '*.cxx' \
 '*.el' '*.f' '*.f90' '*.h' '*.in' '*.in.l' '*.java' \
 '*.mm' '*.pike' '*.py' '*.txt' '*.vim' |
egrep -z -v '^(Utilities/cm|Source/(kwsys|CursesDialog/form)/)' |
egrep -z -v '^(Modules/CPack\..*\.in)' |
xargs -0 sed -i 's/ \+$//'

Source/cmSetDirectoryPropertiesCommand.h

@@ -17,7 +17,7 @@
 class cmSetDirectoryPropertiesCommand : public cmCommand
 {
 public:
-  virtual cmCommand* Clone() 
+  virtual cmCommand* Clone()
     {
       return new cmSetDirectoryPropertiesCommand;
     }
@@ -46,7 +46,7 @@ public:
     {
     return "Set a property of the directory.";
     }
-  
+
   /**
    * Static entry point for use by other commands
    */
@@ -69,7 +69,7 @@ public:
         "ADDITIONAL_MAKE_CLEAN_FILES is a list of files that will be cleaned "
         "as a part of \"make clean\" stage.";
     }
-  
+
   cmTypeMacro(cmSetDirectoryPropertiesCommand, cmCommand);
 };