Version number counting only looks for annotated tags. Re #4765.

The code that determines the 'patch' version number uses 'git describe'.
This change means that git lightweight tags are not considered here,
so we can use them if needed without resetting the version number.

Code/Mantid/Build/CMake/CommonSetup.cmake

@@ -82,7 +82,7 @@ set ( NOT_GIT_REPO "Not" )
 find_package ( Git )
 if ( GIT_FOUND )
   # Get the last revision
-  execute_process ( COMMAND ${GIT_EXECUTABLE} describe --tags --long 
+  execute_process ( COMMAND ${GIT_EXECUTABLE} describe --long
                     OUTPUT_VARIABLE GIT_DESCRIBE
                     ERROR_VARIABLE NOT_GIT_REPO
                     WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}