Add free function for freeing the custom structs.

src/custom.c

@@ -0,0 +1,13 @@
+#include "custom.h"
+
+void libab_behavior_free(libab_behavior* behavior) {
+    libab_parsetype_free_recursive(behavior->type);
+}
+
+void libab_operator_free(libab_operator* op) {
+    libab_behavior_free(&op->behavior);
+}
+
+void libab_function_free(libab_function* fun) {
+    libab_behavior_free(&fun->behavior);
+}

src/table.c

@@ -69,8 +69,8 @@ void libab_table_free(libab_table* table) {
 }
 void libab_table_entry_free(libab_table_entry* entry) {
     if(entry->variant == ENTRY_OP) {
-        libab_parsetype_free_recursive(entry->data_u.op.behavior.type);
+        libab_operator_free(&entry->data_u.op);
     } else if(entry->variant == ENTRY_FUN) {
-        libab_parsetype_free_recursive(entry->data_u.function.behavior.type);
+        libab_function_free(&entry->data_u.function);
     }
 }