[Mathlib-develop] Change to MathLibObject/VariableList implementation

[mark <msp...@ya...>]

Hi,

Both the MathLibObject and the VariableList classes implement lists of na=
med=20
variables. They are both implemented using ArrayLists.

This is ineficient since when finding a variable by name it is necessary =
to=20
iterate through the list until we find the correct variable.

I think that it would be better to implement these classes using a HashMa=
p=20
since it would speed up variable access and is a better fit to the proble=
m.

The only downside I can see is that the code needed to iterate through a=20
hashes key/value pairs is, to put it politely, suboptimal.

What I will most likely do is work on this in a local copy of the code an=
d=20
only commit it if there aren't any problems.

Any comments?
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Best Regards

Mark Sparshatt