doxygen: remove a few comments

These comments were either wrong or non-informative.
Replace some of them by brief comments

Source/cmForEachCommand.h

@@ -16,11 +16,6 @@
 #include "cmFunctionBlocker.h"
 #include "cmListFileCache.h"
 
-/** \class cmForEachFunctionBlocker
- * \brief subclass of function blocker
- *
- * 
- */
 class cmForEachFunctionBlocker : public cmFunctionBlocker
 {
 public:
@@ -37,11 +32,7 @@ private:
   int Depth;
 };
 
-/** \class cmForEachCommand
- * \brief starts an if block
- *
- * cmForEachCommand starts an if block
- */
+/// Starts foreach() ... endforeach() block
 class cmForEachCommand : public cmCommand
 {
 public:

Source/cmFunctionBlocker.h

@@ -17,11 +17,6 @@
 #include "cmListFileCache.h"
 class cmMakefile;
 
-/** \class cmFunctionBlocker
- * \brief A class that defines an interface for blocking cmake functions
- *
- * This is the superclass for any classes that need to block a cmake function
- */
 class cmFunctionBlocker
 {
 public:

Source/cmFunctionCommand.h

@@ -15,11 +15,6 @@
 #include "cmCommand.h"
 #include "cmFunctionBlocker.h"
 
-/** \class cmFunctionFunctionBlocker
- * \brief subclass of function blocker
- *
- *
- */
 class cmFunctionFunctionBlocker : public cmFunctionBlocker
 {
 public:
@@ -35,11 +30,7 @@ public:
   int Depth;
 };
 
-/** \class cmFunctionCommand
- * \brief starts an if block
- *
- * cmFunctionCommand starts an if block
- */
+/// Starts function() ... endfunction() block
 class cmFunctionCommand : public cmCommand
 {
 public:

Source/cmIfCommand.h

@@ -15,11 +15,6 @@
 #include "cmCommand.h"
 #include "cmFunctionBlocker.h"
 
-/** \class cmIfFunctionBlocker
- * \brief subclass of function blocker
- *
- * 
- */
 class cmIfFunctionBlocker : public cmFunctionBlocker
 {
 public:
@@ -39,11 +34,7 @@ public:
   unsigned int ScopeDepth;
 };
 
-/** \class cmIfCommand
- * \brief starts an if block
- *
- * cmIfCommand starts an if block
- */
+/// Starts an if block
 class cmIfCommand : public cmCommand
 {
 public:

Source/cmMacroCommand.h

@@ -15,11 +15,6 @@
 #include "cmCommand.h"
 #include "cmFunctionBlocker.h"
 
-/** \class cmMacroFunctionBlocker
- * \brief subclass of function blocker
- *
- *
- */
 class cmMacroFunctionBlocker : public cmFunctionBlocker
 {
 public:
@@ -35,11 +30,7 @@ public:
   int Depth;
 };
 
-/** \class cmMacroCommand
- * \brief starts an if block
- *
- * cmMacroCommand starts an if block
- */
+/// Starts macro() ... endmacro() block
 class cmMacroCommand : public cmCommand
 {
 public:

Source/cmWhileCommand.h

@@ -16,11 +16,6 @@
 #include "cmFunctionBlocker.h"
 #include "cmListFileCache.h"
 
-/** \class cmWhileFunctionBlocker
- * \brief subclass of function blocker
- *
- * 
- */
 class cmWhileFunctionBlocker : public cmFunctionBlocker
 {
 public:
@@ -37,11 +32,7 @@ private:
   int Depth;
 };
 
-/** \class cmWhileCommand
- * \brief starts a while loop
- *
- * cmWhileCommand starts a while loop
- */
+/// \brief Starts a while loop
 class cmWhileCommand : public cmCommand
 {
 public: