New API introduction
Frame and quixote module API docs in their own files
QElement API docs in its own file
Descriptor API docs are in their own file
API doc tweaks
INTEGRATE: API documentation split into multiple files

* dev:
  API doc tweaks
  Descriptor API docs are in their own file
  QElement API docs in its own file
  Frame and quixote module API docs in their own files
  New API introduction