stack: get stack data directly from stack and remove stackdata()
stackdata function began its life in 137f8b04901e as a proto-stack: it computed
stack revs on its own and only had one property to return, "changesetcount".
Later it started to prepare and return more properties, but since b933a8068c17
it was computing revs using a getstack function. And then finally in
17749d9d3968 it started to rely on stack class entirely.
It was a good function, but now, when all the logic it provided was factored
into stack class, I'd say it's finally time for it to be put to rest.
Doc is generated with sphinx.
You can generate the doc with:
```
make
```
# Tutorials
For updating the tutorials, you need to have the docgraph extension installed
(https://pypi.python.org/pypi/hg-docgraph).
Then run the test-topic-tutorial.t and test-tutorial.t to update the output if
needed.
You'll need the dot binary (likely installed by the graphviz package in your
package manager) in order to have graphviz graphs rendered in the html output.
Simply run make in the docs directory should takes care of the conversion of
the tutorial .t files into .rst files. Then sphinx should do the rest of the
jobs by rendering graphviz graphs.