Generic inference (#2475)

* Change generic symbol resolution.
* Infer generic parameters lhs -> rhs: `List{int} x = list::NOHEAP`.
* Regression: Compiler segfault when assigning struct literal with too few members #2483

test/test_suite/struct/too_few_elements.c3

@@ -0,0 +1,13 @@
+import std;
+fn int main()
+{
+	Colour col = {255, 255, 0}; // #error: Too few elements in initializer
+	return 0;
+}
+struct Colour
+{
+	char a;
+	char r;
+	char g;
+	char b;
+}