ref #1701 [added external renderer interface]
ref #1701 [fixed external renderer interface]

- implemented publishing with rendering into external renderer
'dev' -> 'issues/1701-browser-api'
ref #1701 [trying out new fixes to the library interface]
ref #1701 [added build version and external renderer check]
ref #1671 [final fixes for SEGFAULT bug]

- removed excessive logging
- buffers will be dumped only if log level is set to "all"
[untracked] fixed crash after stopping fetching
[untracked] added windows control logic

- now windows can be brought to front and arranged on the screen from
within the demo application
updated library interface description
ref #1701 [updated library interface for fetching with external renderers]
'issues/1701-browser-api' -> 'dev'