Radical.utils

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- add default config
- config inheritance
- munch implementation / improvements / type checking
- add several tests
- depend on radical.gtod
- documentation
- implement metric_expand
- line buffering is now multiprocess-safe for high-frequency writes
- revert to exec, capture stdio, exceptions
- travis- and pylint-related updates
- apply exception chaining
- sets min python version to 3.6

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- merge 230: test update
- merge 232: documentation fix
- merge 233: pep8
- merge 234: improve test coverage
- merge 235: configurable csv field size limit
- add lock unregister
- clarify cb semantics
- force flush on json write
- make bulk logger usable for tests
- profiling fix
- fix queue debug verbosity
- terminate listerer on unsubscribe
- travis timeout fix

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- fix listener termination for Queue getter

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- improve unit testing

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- fix atfork default setting

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- fix: clean ZMQ subscriber and listener threads after fork
- fix: re-enable atfork handlers for os.fork, logging, singleton by default
- PR 216 fix to_tuple
- PR 217 add time simulation class
- PR 218 change ZMQ bulking defaults
- PR 225 add noop() as cb default value
- remove deprecated signals
- reduce log chattiness
- simplify bridge construction