Merge tag '0.3.1' into develop

v0.3.1
Fixes for mainloop tests
Started adding example
Added finally_action
Added more tests for if_then
Added take_last
Adding tests for do_action
Added skip_last
Added take_last_buffer + cleanup
Added distinct
Added default_if_empty
Cleanup
Added exclusive
Added observable exclusive
Finished tests for expand
Tests and fixes for firstordefault
Removed debug
Added last and lastordefault
Removed unneeded import
Parameter is optional