Implemented boolean operators

tests/programs/branch.q

@@ -25,15 +25,15 @@ main() {
 		exit(1)
 	}
 
-	if x >= 1 || 1 <= x {
+	if x >= 1 {
 		exit(1)
 	}
 
-	if x == inc(x) || x == dec(x) {
+	if 1 <= x {
 		exit(1)
 	}
 
-	if inc(0) == x || dec(0) == x || inc(x) == dec(x) {
+	if x + 1 != x + 1 {
 		exit(1)
 	}
 
@@ -41,7 +41,23 @@ main() {
 		exit(1)
 	}
 
-	if x + 1 != x + 1 {
+	if x - 1 != dec(x) {
+		exit(1)
+	}
+
+	if inc(x) != x + 1 {
+		exit(1)
+	}
+
+	if dec(x) != x - 1 {
+		exit(1)
+	}
+
+	if x != inc(dec(x)) {
+		exit(1)
+	}
+
+	if inc(dec(x)) != x {
 		exit(1)
 	}