Split `--debug` mode into several flags
I guess the time had come to think of splitting `--debug` mode, which was originally designed solely for visualization tools integration, into several meaningful compilation options / flags:

1. Store positions of attributes in the stream — `my_obj._debug['attr_id']`
  1.1. May be additional submode — store positions of individual elements in the array
2. Read-in-constructor vs separate constructor + `_read()` call
3. Dump sequence of `seq` elements as array — `MyType::SEQ_FIELDS`

May be also we could think of:

* dump `doc` / `doc-ref` elements as strings for visualization tools to annotate fields
* dump other metainformation (`title`, `license`, etc) as strings
* dump unofficial YAML fields (i.e. stuff like `-webide-representation`, etc) as is into relevant parts of the class
* for hardcore languages such as C++ — preparing arrays of getter function pointers, i.e. something like:

The main concern is that (1) is super slow and actually rarely needed outside of visualization / debugging purposes. (2) is super useful per se for parsing "bad" data and being able to cope with half-filled classes. (3) is not a big deal, but it adds extra pollution and, again, is pretty much useless outside of scope of vis tools.

From top of my head, I'd go with `--debug-pos` for (1), `--no-ctor-read` for (2), `--debug-seq` for (3).