New design of interface for Airviro dispersion results and time-series of fields in general
Tests added for the interface
Modification of the Edb class to inherit from DatabaseIdentifier
Adaption of stream.py to support any database defined by a DatabaseIdentifier

Minor bugs fixed in datatable

MOdification of
Added a get_loglevel function, and microg2ppb
Added NOx2NO2 adjusted to use new Result interface
Merge branch 'feature/streamres' into develop