Added deprecated ROOT library - geocad

• ROOT dropped geocad from their code base, which some npdet tools were using. This was copied to npdet and added to a new library.
• Added geocad library build
• New cmake flag USE_GEOCAD is automatically set if OpenCascade is found.
• Executable under tools, npdet_to_step is now available again.
• The geocad related tools still need to be fully debugged as the version of opencascade has changed since it was removed from ROOT.