EDF Import: invalid char & overlapping annotations
EDF Import: invalid char & overlapping annotations

Relate to the issue: https://github.com/mne-tools/mne-python/issues/3420
- skip invalid characters in EDF file annotations
- warn for not implementation of overlapping annotations instead of raising an error
Teekuningas/mne-python,wmvanvliet/mne-python,nicproulx/mne-python,wmvanvliet/mne-python,jniediek/mne-python,nicproulx/mne-python,pravsripad/mne-python,wmvanvliet/mne-python,pravsripad/mne-python,olafhauk/mne-python,alexandrebarachant/mne-python,jmontoyam/mne-python,Teekuningas/mne-python,larsoner/mne-python,olafhauk/mne-python,kingjr/mne-python,adykstra/mne-python,rkmaddox/mne-python,drammock/mne-python,bloyl/mne-python,cjayb/mne-python,larsoner/mne-python,Eric89GXL/mne-python,jaeilepp/mne-python,kambysese/mne-python,teonlamont/mne-python,teonlamont/mne-python,jmontoyam/mne-python,kingjr/mne-python,kambysese/mne-python,larsoner/mne-python,adykstra/mne-python,olafhauk/mne-python,pravsripad/mne-python,drammock/mne-python,bloyl/mne-python,kingjr/mne-python,drammock/mne-python,jniediek/mne-python,rkmaddox/mne-python,jaeilepp/mne-python,mne-tools/mne-python,Teekuningas/mne-python,cjayb/mne-python,Eric89GXL/mne-python,alexandrebarachant/mne-python,mne-tools/mne-python,mne-tools/mne-python