Cleanup for nilable types

[geekrelief]

elvis/elvis.nim

Lines 20 to 23 in 1ad14f1

	template truthy*[T](val: ref T): bool = not val.isNil
	template truthy*[T](val: ptr T): bool = not val.isNil
	template truthy*(val: pointer): bool = not val.isNil
	template truthy*(val: ref | ptr | pointer): bool = not val.isNil

We only need the last line with the typeclass. It's equivalent to the top three. https://nim-lang.github.io/Nim/manual.html#generics-type-classes

[mattaylor]

done