Added XML schema files and enriched configuration file with their URLS and related XMLNS prefixes
Separated time and temperature units conversion functions in different modules and refactored imports@
Renamed converter.py to timeformatutils.py and added its new unit test. Updated then imports and references
Refactored the 'to ISO9601' time conversion function
Refactoring of timeformats conversion functions: model entity classes no longer check for time format types but they delegate to lower-level utilities
Code is now aligned to what docs say - I forgot to add a function on the last commit
Refactoring of temperature unit conversions functions