Preparing for v0.4

I'm going to be learning OpenCL, after which I will decide whether to
use OpenCL or OpenMP for the development of Indivisible. This mostly
depends on the compatibility of each library with GMP, especially since
I believe GMP already does some of its own threading.

src/main.c

@@ -11,7 +11,7 @@ static bool run;
 void leave();
 
 int main(void) {
-	puts("Indivisible v0.3\n");
+	puts("Indivisible v0.4\n");
 
 	// Quit on ^C by setting `run = false'
 	run = true;