Use 'not' instead of '!' for boolean not operation

This makes it consistent with the 'and' and 'or' operators

bin/varnishtest/tests/l00001.vtc

@@ -145,8 +145,8 @@ logexpect l1 -d 1 -g vxid -q "RespStatus == 404 or RespStatus ~ '^200$'" {
 	expect * =	End
 } -run
 
-# Test boolean !
-logexpect l1 -d 1 -g vxid -q "RespStatus == 404 or !RespStatus ~ '^404$'" {
+# Test boolean not
+logexpect l1 -d 1 -g vxid -q "RespStatus == 404 or not RespStatus ~ '^404$'" {
 	expect 0 *	Begin	req
 	expect * =	ReqEnd
 	expect * =	End

lib/libvarnishapi/generate.py

@@ -60,9 +60,10 @@ tokens = {
         # Boolean operators
         "T_AND":        "and",
         "T_OR":         "or",
+	"T_NOT":	"not",
 
         # Miscellaneous
-        None:           "<>~![]{}()",
+        None:           "<>~[]{}()",
 
         # These have handwritten recognizers
         "VAL":          None,

lib/libvarnishapi/vsl_query.c

@@ -236,7 +236,7 @@ vslq_exec(const struct vex *vex, struct VSL_transaction * const ptrans[])
 		if (r <= 0)
 			return (r);
 		return (vslq_exec(vex->b, ptrans));
-	case '!':
+	case T_NOT:
 		AN(vex->a);
 		AZ(vex->b);
 		r = vslq_exec(vex->a, ptrans);

lib/libvarnishapi/vxp_parse.c

@@ -304,7 +304,7 @@ vxp_expr_group(struct vxp *vxp, struct vex **pvex)
 /*
  * SYNTAX:
  *   expr_not:
- *     '!' expr_group
+ *     'not' expr_group
  *     expr_group
  */
 
@@ -315,7 +315,7 @@ vxp_expr_not(struct vxp *vxp, struct vex **pvex)
 	AN(pvex);
 	AZ(*pvex);
 
-	if (vxp->t->tok == '!') {
+	if (vxp->t->tok == T_NOT) {
 		ALLOC_OBJ(*pvex, VEX_MAGIC);
 		AN(*pvex);
 		(*pvex)->tok = vxp->t->tok;