Use %f instead of %g in AST dumps

- To ensure that floating point constants are identifiable as floating
  point, FLispString::AddFloat() now prints them with %f.

src/zscript/ast.cpp

@@ -155,7 +155,7 @@ public:
 	void AddFloat(double f)
 	{
 		char buf[32];
-		size_t len = mysnprintf(buf, countof(buf), "%g", f);
+		size_t len = mysnprintf(buf, countof(buf), "%.4f", f);
 		Add(buf, len);
 	}
 private: