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

spec/test_user_context_fields.d

@@ -10,9 +10,9 @@ int main()
 unittest
 {
     string input = "aaa\n\n\na\n    # comment 1\na  a    aa\n\naa\n#    comment 2\na\n";
-    p_context_t context;
-    p_context_init(&context, input);
-    assert(p_parse(&context) == P_SUCCESS);
+    p_context_t * context;
+    context = p_context_new(input);
+    assert(p_parse(context) == P_SUCCESS);
 
     stderr.writeln("comments: ", context.comments);
     stderr.writeln("acount: ", context.acount);