Fix edata to df (#608)
Fix edata to df (#608)

* add by_id option to dataframe construction

* allow to pass single edata, rdata to pandas._AsDataFrame

* tidy up AsDataFrame methods

* also add by_id to FromDataFrame methods

* fix codacy

* fix codacy no 2

* autopep8 pandas.py

* docstring: mention that we allow single instances

* pandas.py::_get_names_or_ids: customize error output by by_id

* amici.amici. -> amici.

* hasObservableNamesIds -> by variable

* try back amici. -> amici.amici.

* also check for pointers

FFroehlich/AMICI,AMICI-developer/AMICI,AMICI-developer/AMICI,FFroehlich/AMICI,FFroehlich/AMICI,AMICI-developer/AMICI,FFroehlich/AMICI,AMICI-developer/AMICI