Use `opts_add` in `drawBarseries`
Stacked bar plots together with others
Add test `stackedBarsWithOther`
Remove quirky barplots bail-out

This seems not to be needed anymore.
In both R2014a and R2014b, the `ACID(104)` test `stackedBarsWithOther`
runs completely fine on `pgfplots 1.10`.

As such, we don't need to warn about this anymore.
Merge branch 'barplots' to fix #442

Tested in R2014a, `ACID(104)` also in R2014b.
Since this was a TikZ incompatibility and not a MATLAB/m2t one,
test coverage of 1 environment is enough.
However, I haven't determined the minimal `pgfplots` version for this
to work. Using `pgfplots 1.11` (and I think I previously also did some tests
using `pgfplots 1.10`) works, using the compatibility mode of `pgfplots` down
to `1.3` gave no errors in `1.11`, but that's hardly a guarantee it will work
in `1.3`, I think.