Release 0.8.0

"[#201] Implement fetch() in the DAS API
[#223] Updates in docstrings and logging messages
[#210] Improve message error when connecting to the server
[#214] Improve fetch() method to optionally fetch all the atoms
[#241] Fix tests
[#213] Add TraverseEngine to API documentation
[#114] Persist new atoms in remote server
[#216] Changed design for custom filters in TraverseEngine
[#229] Improve error handler
[#218] Make a DAS server read-only
[#223] Updated kwargs documentation
[#268] Adding performance tests in MeTTa
[#268] enhancing perf tests script, added results comparison
[#276] API support to AtomDB new queries"