flake8: document all the exception we added

README: mention the addition of the topic extensions That is probably worth noting.

tests: run pyflake on all python files We have fixed the handfull of error pyflakes found on evolve so we can setup the test to prevent regression. Next stop flake8.

serveronly: fix undefined variable This is a legit bug caught by pyflake

legacy: properly test for mercurial version in the legacy extensions Otherwise 'demandimport' would delay the raising of ImportError.

evolve: prevent global variable shadowing Small and harmless pyflake complains.

evolve: drop some unused variables More pyflakes catches.

evolve: drop some unused import topic came with pyflake checking, let us make use of it.

README: fix evolve installation path We forgot to do so when we moved things to hgext3rd.

topic: merge the topic extension in the evolve repository There is a lot of synergy between the two concepts. Topic is expected to be able to smooth multiple of evolution sharp edge. Having them both in the same repository will make this collaboration easier.