Simplify libmadx.get_table return signature
Include formatted remote traceback in exceptions

This makes it possible to see the remote traceback. Note, that all
custom arguments and attributes of the exception are dropped, so don't
do anything special!
Merge branch 'remote-exception-traceback' into redesign-cpymad-backend
Merge branch 'remote-exception-traceback' into simplify-libmadx-gettable
Fix str.split in libmadx._split_header_line

str.split expects the 'maxsplit' parameter as its *second* *non-keyword*
argument.
Use more idiomatic Cython C-array iteration
Merge branch 'simplify-libmadx-gettable' into redesign-cpymad-backend