Extend switch action to support switching to non-file buffers
Merge pull request #477 from joelmo/master

Extend switch action to support source.buffer
Delete undo source
Revert "Delete undo source"

This reverts commit a1d3f4e4711177cff0af5b59276b3d22aaa2ccda.
Delete undo source
Fix unite__new_candidate problem
Merge