I am trying to use Lasem through PyGI, in which I have trouble.
The function annotations seem to be incorrect,
which makes the gi interface not usable.

The list of APIs whose annotations I think is incorrect:
* `lsm_dom_document_append_from_memory` and `lsm_dom_document_new_from_memory`:
  The type of the argument `buffer` is `const void*`,
  which in PyGI it accepts neither string nor `bytes`,
  instead it accepts integer. It should be `const char*` so that
  I can pass string.
* `lsm_dom_document_save_to_memory`: The type of the argument `buffer`
  should be `char**` and it should be marked as “out”.
* `lsm_dom_view_get_size` and `lsm_dom_view_get_size_pixels`:
  The arguments `width`, `height` and `baseline` should be marked as “out”
  so that they will be returned as return value in PyGI, not arguments
  that I need to pass pointers, which is impossible in Python.