Potential bug in /sharpy/aero/modals/aerogrid.py

**Describe the bug**
In lines 273, 280 and 313, according to the Aerodynamics input h5file: I think that the control surface info `['control_surface_hinge_coords']` should be `['control_surface_hinge_coord']`.
Thank you.

Inspect sharpy/aero/modals/aerogrid.py at lines 273, 280, and 313, then compare the referenced control-surface key with the Aerodynamics input HDF5 file format. The issue is complete when all three references use the key that matches the input format and the affected loading paths continue to work.

Written by the indexing model from the issue text.