evolve: add pre-check logic for content-divergence in rewriteutil.precheck()
For now, pre-check will abort if rewriting a rev create divergence (and
config experimental.evolution.allowdivergence is not set to True).
But this behaviour can be improved where instead of abort maybe we
can confirm the user to either proceed with divergence or some other
options depends on what command user is running.
Changes in test file are used to overrides the pre-check for testing
purpose (using experimental.evolution.allowdivergence=yes).
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.