Change syntax of $if, $assert, $include, $echo. Introduces $error

resources/testproject/hello_world.c3

@@ -1,7 +1,7 @@
 module hello_world;
 import std;
 import bar;
-$if (env::os_is_win32())
+$if env::os_is_win32():
 fn int test_doubler(int x)
 {
 	return x * x;