Replace matchTolerance with assert_equal

[Puzzled-Face]

Write an assert_equal checkmate-like function and use it as a replacement for matchTolerance.

See #683 for details.

[Puzzled-Face]

The title of this issue is misleading. An assert_equal function is not a replacement for matchTolerance. Given a value (in its first argument), a list/vector (in its second argument) and a tolerance (in its third), matchTolerance selects the (first) match to the value from the vector/list that is within tolerance. It does not confirm that the value(s) in the first argument are all present in the second argument, allowing for given tolerance.

Therefore, it would be better simply to rename matchTolerance to match_within_tolerance.