Fixed annotation for Python 3.9

Handle datetime depricataion

Make deepcopy of data_dict on dump adi/adx to not change provided data

Fixed test case for latin1 file

Fixed generating missing header fields in adi.dump*()

Added test for unmodified data_dict

Added adi.loadi() to be able to efficiently watch ADI files for changes

Fixed allow LF and CR as ASCII chars (for NOTES etc)

Fixed tests to use abspath

- Bugfixes and tests

- Exception on non ASCII chars

- Accept userdef on load and dump