Added direct force plugin and fixes in stretching energy

Samo Penic

2019-03-09 2c4278db6ead5c27e30a3000097ed898c968534e

 src/io.c

@@ -1205,12 +1205,23 @@
   CFG_SIMPLE_FLOAT("c0",&tape->c0),
   CFG_SIMPLE_FLOAT("w",&tape->w),
   CFG_SIMPLE_FLOAT("F",&tape->F),
/* Variables related to plane confinement */
   CFG_INT("plane_confinement_switch", 0, CFGF_NONE),
   CFG_FLOAT("plane_d", 15, CFGF_NONE),
   CFG_FLOAT("plane_F", 1000, CFGF_NONE),
/* Variables related to stretching */
//   CFG_FLOAT("stretchswitch", 0, CFGF_NONE),
//   CFG_FLOAT("xkA0",0,CFGF_NONE),
        CFG_END()
    };
    cfg_t *cfg;    
    ts_uint retval;
    cfg = cfg_init(opts, 0);
    retval=cfg_parse_buf(cfg, buffer);
   tape->plane_confinement_switch=cfg_getint(cfg,"plane_confinement_switch");
   tape->plane_d=cfg_getfloat(cfg,"plane_d");
   tape->plane_F=cfg_getfloat(cfg,"plane_F");

    if(retval==CFG_FILE_ERROR){
   fatal("No tape file.",100);
   }