Added constant volume plugin (partially)

Samo Penic

2019-03-08 77a2c7de0dd6563a30467fa2e73f02ec9f4c3deb

 src/general.h

@@ -313,6 +313,7 @@
   ts_double (*vm_energy_before_execute)(void *vesicle, ts_vertex *vtx);
   ts_double (*vm_energy_after_prepare)(void *vesicle, ts_vertex *vtx);
   ts_double (*vm_energy_after_execute)(void *vesicle, ts_vertex *vtx);
   ts_double (*vm_before_montecarlo_constraint)(void *vesicle, ts_vertex *vtx, ts_vertex *old_vtx);
   ts_double (*vm_new_state_accepted)(void *vesicle, ts_vertex *vtx);
   ts_double (*vm_new_state_rejected)(void *vesicle, ts_vertex *vtx);
   void (*cleanup)(void);
@@ -344,6 +345,7 @@
   ts_plugin_chain *vm_hard_constraint;
   ts_plugin_chain *vm_energy_before_prepare;
   ts_plugin_chain *vm_energy_after_execute;
   ts_plugin_chain *vm_before_montecarlo_constraint;
   ts_plugin_chain *cleanup;
} ts_plugin_chains;