The parameter parser specifically looked for the old bracket syntax.
This generated a lot of warnings when building the docs. Those warnings
have been fixed by changing the parsing logic.

Signed-off-by: Trevor Norris <trev.norris@gmail.com>

Add HasExternalData API to check if Object has externally allocated
memory, and accompanying tests.

smalloc.alloc now accepts an optional third argument which allows
specifying the type of array that should be allocated. All available
types are now located on smalloc.Types.

It will be confusing if later on we add Buffer#dispose(), and smalloc is
its own cpp api anyways. So instead create a new require('smalloc') to
expose the previous Buffer.alloc/dispose methods, and expose copyOnto
and kMaxLength as well.

Other changes:
* Added documentation and additional tests.
* smalloc::CopyOnto has changed from using assert() to throwing errors
  on bad argument values because it is not exposed to the user.
* Minor style fixes.