Implemented equality/pattern matching support.

Introduced a new event:

  match(pattern,groundterm)

This event can only be executed if pattern can be matched to groundterm.
Variable substitutions are persistent with respect to later events in
the same role.

Currently implemented as syntactic sugar, essentially unfolded in role R to:

  fresh x;
  send ( R,R, { groundterm }x );
  recv ( R,R, { pattern }x );

This work is not complete yet in the send that the output still contains
the unfolding. Ideally, the graph rendered detects this syntactic sugar
and renders a simplified event. This should be possible on the basis of
the label name prefix.

Conflicts:
	src/compiler.c
	src/parser.y
	src/scanner.l
	src/tac.h

src/parser.y

@@ -57,6 +57,7 @@ int yylex(void);
 %token 		HASHFUNCTION
 %token		KNOWS
 %token		TRUSTED
+%token 		MATCH
 
 %type	<tac>	spdlcomplete
 %type	<tac>	spdlrep
@@ -196,6 +197,15 @@ event		: READT label '(' termlist ')' ';'
 			t->t2.tac = $4;
 			$$ = t;
 		  }
+		| MATCH '(' term ',' term ')' ';'
+		  {
+		  	/* first argument is pattern, second should be
+			 * ground term */
+		  	Tac t= tacCreate(TAC_MATCH);
+			t->t1.tac = $3;
+			t->t2.tac = $5;
+			$$ = t;
+		  }
 		| CLAIMT optlabel '(' termlist ')' ';'
 		/* TODO maybe claims should be in the syntax */
 		  {	Tac t = tacCreate(TAC_CLAIM);