Fix Place __getitem__ behavior.
Fix Place __getitem__ behavior.

Place.__getitem__ was implemented to return the x- and
y-parts of the place. In the regular case it simply
returns the components. In the discriminant case it
returns the x- and y-projections onto the curve.

abelfunctions/abelfunctions,cswiercz/abelfunctions,abelfunctions/abelfunctions,abelfunctions/abelfunctions,cswiercz/abelfunctions,cswiercz/abelfunctions