Check that out-of-bounds access on a dynamic array or queue works and
returns the correct value.
* 2-state vectors: '0 with the element width
* 4-state vectors: 'x with the element width
* reals: 0.0
* strings: ""
Note that the 2-state test currently still fails as out-of-bounds access on
a 2-state vector incorrectly returns 'x.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>