Replace p_context_init() with p_context_new()/p_context_delete()

spec/test_parser_rule_user_code.c

@@ -5,9 +5,10 @@
 int main()
 {
     char const * input = "ab";
-    p_context_t context;
-    p_context_init(&context, (uint8_t const *)input, strlen(input));
-    assert(p_parse(&context) == P_SUCCESS);
+    p_context_t * context;
+    context = p_context_new((uint8_t const *)input, strlen(input));
+    assert(p_parse(context) == P_SUCCESS);
+    p_context_delete(context);
 
     return 0;
 }