Uninstall support, pinched from OSG.

CMakeModules/cmake_uninstall.cmake.in

@@ -0,0 +1,22 @@
+IF(NOT EXISTS "@CMAKE_CURRENT_BINARY_DIR@/install_manifest.txt")
+    MESSAGE(FATAL_ERROR "Cannot find install manifest: \"@CMAKE_CURRENT_BINARY_DIR@/install_manifest.txt\"")
+ENDIF()
+
+FILE(READ "@CMAKE_CURRENT_BINARY_DIR@/install_manifest.txt" files)
+STRING(REGEX REPLACE "\n" ";" files "${files}")
+
+FOREACH(file ${files})
+    MESSAGE(STATUS "Uninstalling \"${file}\"")
+    IF(EXISTS "${file}")
+        EXEC_PROGRAM(
+            "@CMAKE_COMMAND@" ARGS "-E remove \"${file}\""
+            OUTPUT_VARIABLE rm_out
+            RETURN_VALUE rm_retval
+            )
+        IF(NOT "${rm_retval}" STREQUAL 0)
+            MESSAGE(FATAL_ERROR "Problem when removing \"${file}\"")
+        ENDIF()
+    ELSE()
+        MESSAGE(STATUS "File \"${file}\" does not exist.")
+    ENDIF()
+ENDFOREACH()