Fix Ox implementation

Remove .h from Ox, fix `lex` typo, and add samples for Ox.

samples/Ox/ParallelObjective.ox

@@ -0,0 +1,63 @@
+/** Client and Server classes for parallel optimization using CFMPI.**/
+#include "ParallelObjective.h"
+
+/** Set up MPI Client-Server support for objective optimization.
+@param obj `Objective' to parallelize
+@param DONOTUSECLIENT TRUE (default): client node does no object evaluation<br>FALSE after putting servers to work Client node does one evaluation.
+**/
+ParallelObjective(obj,DONOTUSECLIENT) {
+	if (isclass(obj.p2p)) {oxwarning("P2P object already exists for "+obj.L+". Nothing changed"); return;}
+	obj.p2p = new P2P(DONOTUSECLIENT,new ObjClient(obj),new ObjServer(obj));
+	}
+
+ObjClient::ObjClient(obj) { this.obj = obj;    }
+
+ObjClient::Execute() {    }
+
+ObjServer::ObjServer(obj) {
+    this.obj = obj;
+    basetag = P2P::STOP_TAG+1;
+    iml = obj.NvfuncTerms;
+    Nparams = obj.nstruct;
+    }
+
+/** Wait on the objective client.
+**/
+ObjServer::Loop(nxtmsgsz) {
+    Nparams = nxtmsgsz;   //free param length is no greater than Nparams
+    if (Volume>QUIET) println("ObjServer server ",ID," Nparams ",Nparams);
+    Server::Loop(Nparams);
+    Recv(ANY_TAG);                      //receive the ending parameter vector
+    obj->Encode(Buffer[:Nparams-1]);   //encode it.
+    }
+
+/** Do the objective evaluation.
+Receive structural parameter vector and `Objective::Encode`() it.
+Call `Objective::vfunc`().
+@return Nparams (max. length of next expected message);
+**/
+ObjServer::Execute() {
+	obj->Decode(Buffer[:obj.nfree-1]);
+	Buffer = obj.cur.V[] = obj->vfunc();
+    if (Volume>QUIET) println("Server Executive: ",ID," vfunc[0]= ",Buffer[0]);
+	return obj.nstruct;
+	}
+
+CstrServer::CstrServer(obj) { ObjServer(obj);	}
+
+SepServer::SepServer(obj) { ObjServer(obj);	}
+
+CstrServer::Execute() {
+	obj->Encode(Buffer);
+	obj->Lagrangian(0);
+	return rows(Buffer = obj.cur->Vec());
+	}
+
+/** Separable objective evaluations.
+**/
+SepServer::Execute() {
+	obj.Kvar.v = imod(Tag-basetag,obj.K);
+	obj->Encode(Buffer,TRUE);
+	Buffer = obj.Kvar->PDF() * obj->vfunc();
+	return obj.NvfuncTerms;
+	}