imported a reworked version of BTL (Benchmark for Templated Libraries).

the modifications to initial code follow:
* changed build system from plain makefiles to cmake
* added eigen2 (4 versions: vec/novec and fixed/dynamic), GMM++, MTL4 interfaces
* added "transposed matrix * vector" product action
* updated blitz interface to use condensed products instead of hand coded loops
* removed some deprecated interfaces
* changed default storage order to column major for all libraries
* new generic bench timer strategy which is supposed to be more accurate
* various code clean-up

bench/btl/cmake/MacroOptionalAddSubdirectory.cmake

@@ -0,0 +1,31 @@
+# - MACRO_OPTIONAL_ADD_SUBDIRECTORY() combines ADD_SUBDIRECTORY() with an OPTION()
+# MACRO_OPTIONAL_ADD_SUBDIRECTORY( <dir> )
+# If you use MACRO_OPTIONAL_ADD_SUBDIRECTORY() instead of ADD_SUBDIRECTORY(),
+# this will have two effects
+# 1 - CMake will not complain if the directory doesn't exist
+#     This makes sense if you want to distribute just one of the subdirs
+#     in a source package, e.g. just one of the subdirs in kdeextragear.
+# 2 - If the directory exists, it will offer an option to skip the 
+#     subdirectory.
+#     This is useful if you want to compile only a subset of all
+#     directories.
+
+# Copyright (c) 2007, Alexander Neundorf, <neundorf@kde.org>
+#
+# Redistribution and use is allowed according to the terms of the BSD license.
+# For details see the accompanying COPYING-CMAKE-SCRIPTS file.
+
+
+MACRO (MACRO_OPTIONAL_ADD_SUBDIRECTORY _dir )
+   GET_FILENAME_COMPONENT(_fullPath ${_dir} ABSOLUTE)
+   IF(EXISTS ${_fullPath})
+      IF(${ARGC} EQUAL 2)
+        OPTION(BUILD_${_dir} "Build directory ${_dir}" ${ARGV1})
+      ELSE(${ARGC} EQUAL 2)
+        OPTION(BUILD_${_dir} "Build directory ${_dir}" TRUE)
+      ENDIF(${ARGC} EQUAL 2)
+      IF(BUILD_${_dir})
+         ADD_SUBDIRECTORY(${_dir})
+      ENDIF(BUILD_${_dir})
+   ENDIF(EXISTS ${_fullPath})
+ENDMACRO (MACRO_OPTIONAL_ADD_SUBDIRECTORY)