- Document global option DelayedArray.block.size

- Add man page and unit tests for statistical methods defined in
  DelayedArray-stats.R

- Make DelayedArray contain Annotated from S4Vectors.

- Add more examples to the man pages (using the toy dataset).

- Add unit tests for round() and signif() (Math2 group).

- Add vignette.

- Support subsetting an arbitrary object by a DelayedArray or
  DelayedMatrix of type logical.

- Support more matrix- and array-like operations.

- How well supported are DelayedArray of type "character"?

- Add more unit tests.

