Re #5556. Use relative paths in installed Mantid.properties

for all platforms (Windows already did). This assists in making
a Mantid install relocatable, which is required for the upcoming
installation on SNS clusters.

Code/Mantid/Framework/Kernel/CMakeLists.txt

@@ -394,24 +394,15 @@ install ( TARGETS Kernel ${SYSTEM_PACKAGE_TARGET} DESTINATION ${LIB_DIR} )
 
 # Create the properties file for the installer
 if ( APPLE )
-  set ( MANTID_ROOT ${CMAKE_INSTALL_PREFIX}/MantidPlot.app )
-elseif ( WIN32 )
-  set ( MANTID_ROOT .. )
+  set ( MANTID_ROOT ../.. )
 else ()
-  set ( MANTID_ROOT ${CMAKE_INSTALL_PREFIX} )
+  set ( MANTID_ROOT .. )
 endif ()
 
-if (WIN32)
-  set ( PLUGINS ${MANTID_ROOT}/${PLUGINS_DIR} )
-  set ( QTPLUGINS ${MANTID_ROOT}/${PLUGINS_DIR}/qtplugins/mantid )
-  set ( COLORMAPS_FOLDER ${MANTID_ROOT}/colormaps )
-  set ( PV_PLUGINS ${MANTID_ROOT}/${PVPLUGINS_DIR} )
-else ()
-  set ( PLUGINS ${CMAKE_INSTALL_PREFIX}/${PLUGINS_DIR} )
-  set ( QTPLUGINS ${CMAKE_INSTALL_PREFIX}/${PLUGINS_DIR}/qtplugins/mantid )
-  set ( COLORMAPS_FOLDER ${CMAKE_INSTALL_PREFIX}/${INBUNDLE}colormaps )
-  set ( PV_PLUGINS ${CMAKE_INSTALL_PREFIX}/${PVPLUGINS_DIR} )
-endif ()
+set ( PLUGINS ${MANTID_ROOT}/plugins )
+set ( QTPLUGINS ${MANTID_ROOT}/plugins/qtplugins/mantid )
+set ( COLORMAPS_FOLDER ${MANTID_ROOT}/colormaps )
+set ( PV_PLUGINS ${MANTID_ROOT}/${PVPLUGINS_SUBDIR} )
 
 set ( PYTHONALGS ${PLUGINS}/PythonAlgs )
 set ( DATADIRS "" )