Add MINIMAL pragma to Vector & MVector type classes

[Shimuuar]

At the moment only checked that MINIMAL is indeed minimal and no method is ⊥ by visual inspection

Fixes #11

[Shimuuar]

Yes, list is indeed minimal. I also thrown in fix for #213

[lehins]

Few suggestion on haddock, otherwise looks great

[lehins]

Suggested change

	-- | Create a mutable vector of the given length. The vector content
	-- should be presumed uninitialized. However exact semantics depends
	-- on vector implementation. For example unboxed and storable
	-- vectors will create vector filled with whatever underlying memory
	-- buffer happens to contain, while boxed vector initializes every
	-- element to @error "..."@.
	-- | Create a mutable vector of the given length. Boxed vector is
	-- initialized with every element set to @error "..."@.
	--
	-- @since 0.5

[Bodigrim]

I'd probably say that elements of boxed vectors are initialized with bottoms, but do not overspecify whether it is error or undefined or another diverging computation.

[Shimuuar]

@lehins Thanks for the suggestion. They definitely improved haddocks. And thanks for finding out those @since pragmas

@Bodigrim Yeah, good idea. I also specified that it's exception throwing bottom.