BUG: Fix ComputeTube(Graph)Probability failing for Xcode builds
BUG: USE_SYSTEM_* is already checked in each External_*.cmake file
BUG: Fix KWStyle dependency added twice
Merge pull request #133 from jamiesnape/FixComputeTubeProbabilityXcode

BUG: Fix ComputeTube(Graph)Probability failing for Xcode builds