Docplex

* In ``docplex.mp``:
* add Model.quadratic_dual_slacks()
* Fixed a bug in multi-objectives: objectives were incorrectly rounded
* Fixed a bug in Model.report(): multiple objective values were not displayed()
* In ``docplex.cp``:
* Add conflict in CPO format in refine conflict result
* Fix problem when parsing KPIs section of a CPO model
* Add method add_constraint() to model for compatibility with docplex.mp
* Comment method get_fail_status() of SolveResult as deprecated.
* Fix problem of wrong import of deque in collections.abc

* Updated tracking events in Watson studio notebooks.
* In ``docplex.mp``:
* Model.solve() will not use solve on cloud unless `agent` is specifically set to 'docloud`.

* Removed dependency to the `docloud` package. Now you need to explicitely install the package using `pip install docloud` to use DOcplexcloud.
* In ``docplex.mp``:
* added Model.export_as_mps_string(), Model.export_as_sav_string()
* fixed a bug with dettime_limit: solving with a deterministic time limit
was mis-interpreted as a solve failure, returning None.
* fixed bug on cplexcloud solve: number of nodes processed was always zero.
* repeated solves incorrectly restarted from start of search, now start from where the last solve stopped.
* added keyword argument 'time_limit' to Model.solve() to set a temporary time limit.
* added new method SolveSolution.is_valid_solution()
* fixed a bug in ModelReader: ranged constraints bounds were inverted when reading from SAV or MPS.
* fixed a bug in Model.set_lex_multiobj(): arguments abstols, reltols were ignored.
* added proper type-checking for Model.add_indicator_constraints()
* added docplex.mp.check_list/py to check local installation.
* In ``docplex.cp``:
* Enable reading of line directives when parsing a CPO file
* Remove parameter LogSearchTags from public parameters
* Fix a minor problem concerning compilation of KPI expressions in CPO format

* In ``docplex.mp``:
* Added a LinearRelaxer class to make a linearized copy of a MIP model (if possible).
see class `docplex.mp.relax_linear.LinearRelaxer`
* Conflict refiner default behavior is now identical to CPLEX interactive
(the new behavior is much faster).
* Bug fixed: expressions of the form k*x did not notify constraints when modified.
* Fixed: message "ignored keyword argument" was incorrectly printed when setting
`cts_by_name=True` in model constructor.

* Added support for CPLEX 12.10
* In ``docplex.mp``:
* Logical expressions, binary variables, and constraints can now be freely nested with logical operators.
* Fixed a print of 'CPLEX Error 1217' in log for multi-objective problems.
* Fixed a bug when setting log_output to a file name: file was created, but empty.

* Fixed bug in logical_and() when result var is set to 0.