Refactor for cleanliness

Move files into separate folders for ease of reading, include source
directory so we can use angle bracket includes, adjust build system to
make directories for objects

lisp/eval.c

@@ -0,0 +1,24 @@
+/* Copyright (C) 2025 Aryadev Chavali
+
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU General Public License Version 2 for
+ * details.
+
+ * You may distribute and modify this code under the terms of the GNU General
+ * Public License Version 2, which you should have received a copy of along with
+ * this program.  If not, please go to <https://www.gnu.org/licenses/>.
+
+ * Created: 2025-04-18
+ * Description: Evaluator implementation
+ */
+
+#include <lisp/eval.h>
+
+err_t eval(context_t *ctx, lisp_t *obj, lisp_t **ret)
+{
+  (void)ctx;
+  (void)obj;
+  (void)ret;
+  TODO("implement evaluator");
+}