build script fails with hepmc3.3
With the latest version of HepMC3 (3.03.00) the rivet build script fails reporting:
configure: error: HepMC3 version 3.1.1 or later is required. configure: HepMC version is 3.03.00 -> 33
it seems to fail to understand the HepMC3 version numbering and thinks 3.1.1>3.03.00