Add inline XOR (^) operator for selectors

[jeroenjanssens]

Description

Selectors support inline AND (&), OR (|), and NOT (~) operators, but not yet the inline XOR (^) operator. Might as well add it for consistency sake. The cs.xor() method does work, so adding the inline version shouldn't be too much work.

[ritchie46]

I will tag @alexander-beedie on this one, given this are the selectors.

[alexander-beedie]

Done (with a couple of bonus selector fixes/updates) 👌

[jeroenjanssens]

Thank you very much, @alexander-beedie. That was quick!