Implementation of SequenceableCollection>>#groupsOf: causes errors

[Gabriel-Darbord]

The extension implementation of SequenceableCollection>>#groupsOf: uses a collection made with self species new to hold groups, however this is problematic when the receiver doesn't support the add: message, such as subclasses of ArrayedCollection.

This method has since been defined in Spec.
Also, I didn't find any sender in the current version of this repo.

Thus, I suggest deleting the method.
Although, if there is still a use for it, relying on Spec will not make it backwards compatible with earlier Pharo versions. Instead, self species new should be replaced with OrderedCollection new.

[jecisc]

If the extension is not used in MDL I'll deprecate and remove it