Squashed 'external/devlib/' changes from 37a6b4f96..7f5e0f5b4

7f5e0f5b4 utils/version: Bump dev version
7e682ed97 target: Check that the connection works cleanly upon connection
62e24c576 connections: Unify BackgroundCommand API and use paramiko for SSH
eb6fa9384 utils/misc: Add redirect_streams() helper
9d5d70564 target: Use tls_property() to manage a thread-local connection
922686a34 utils/misc: Add tls_property()
98e2e51d0 devlib.utils.misc: Use Popen.communicate(timeout=...) in check_output
92e16ee87 instrument/daq: Add an explicit time column to the DAQ measurements
72ded188f instrument/daq: Convert reading rows from all files to a generator
dcab0b371 instrument/daq: Check that self.tempdir has been set before calling os.path.isdir()

git-subtree-dir: external/devlib
git-subtree-split: 7f5e0f5b4ddd205b1d5a1ee1d02dd232d26527f2