add continuous and interaction class-functions which has to be override

Processes/Proposal/ContinuousProcess.h

+/*
+ * (c) Copyright 2018 CORSIKA Project, corsika-project@lists.kit.edu
+ *
+ * See file AUTHORS for a list of contributors.
+ *
+ * This software is distributed under the terms of the GNU General Public
+ * Licence version 3 (GPL Version 3). See file LICENSE for a full version of
+ * the license.
+ */
+
+#ifndef _corsika_process_proposal_interaction_h_
+#define _corsika_process_proposalythia_interaction_h_
+
+#include <PROPOSAL/PROPOSAL.h>
+
+
+namespace corsika::process::proposal {
+
+  class Interaction : public corsika::process::ContinuousProcess<Continuous> {
+  private:
+
+
+  public:
+    template <typename Particle, typename Track>
+    EProcessReturn DoContinuous(Particle&, Track const&) const;
+
+    template <typename Particle, typename Track>
+    units::si::LengthType MaxStepLength(Particle const& p, Track const& track) const;
+  }
+} // namespace corsika::process

Processes/Proposal/Interaction.h

+/*
+ * (c) Copyright 2018 CORSIKA Project, corsika-project@lists.kit.edu
+ *
+ * See file AUTHORS for a list of contributors.
+ *
+ * This software is distributed under the terms of the GNU General Public
+ * Licence version 3 (GPL Version 3). See file LICENSE for a full version of
+ * the license.
+ */
+
+#ifndef _corsika_process_proposal_interaction_h_
+#define _corsika_process_proposalythia_interaction_h_
+
+#include <PROPOSAL/PROPOSAL.h>
+
+
+namespace corsika::process::proposal {
+
+  class Interaction : public corsika::process::InteractionProcess<Interaction> {
+  private:
+
+
+  public:
+    template <typename Particle>
+    EProcessReturn DoInteraction(Particle&);
+
+    template <typename TParticle>
+    corsika::units::si::GrammageType GetInteractionLength(TParticle& p);
+
+  }
+} // namespace corsika::process