Poteat/additional reifications

[poteat]

Kind.Collapse is particularly useful for longer / more complex trees of type manipulation

• Add List.Count to create a frequency map from a list.
• Add List.Same to check if all elements in a list are equal.
• Add Object.AtPathInObject to get the value at a path in an object.
• Reify Object.AtPath to a value-level function.
• Add Object.Defaults to initialize an object with default values.
• Add Object.Omit to remove keys from an object.
• Add Object.Pick to pick keys from an object.
• Reify Object.Values to a value-level function.
• Reify List.Slice and List.Splice to value-level functions.
• Add arg-swapped List.SliceList and List.SpliceList utilities.
• Add List.Entries to get the entries of a list as a list of 2-tuples.
• Add String.Entries to get the entries of a string as a list of 2-tuples.
• Add Kind.Collapse to convert an n-arity kind to a 1-arity kind.