README: add URLs of homepage, primary hg repo, and git mirror repo
Subrepos: generate .hgsubstate and .hgsub based on gitlinks and .gitmodules, preserve gitlinks on hg commit export. Tests included. Dependency from PyPI's ordereddict to use OrderedDict
setup.py: bump version to 0.4.0 on the branch containing submodule support
git_handler: remove tab character that snuck in
submodules: only use the ordereddict backport if collections.OrderedDict is unavailable
Merge master into next.
readme: update supported versions in README.md

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extra : rebase_source : 6f8903304faf139d5df65f5aa79e20e4e86b4de5
tests: upgrade run-tests.py

This is the version from Hg 2.3.

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extra : rebase_source : 2a16446bd40a7514d07c51e47ed34cef3296b652
tests: unify test-keywords

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rename : tests/test-keywords => tests/test-keywords.t
extra : rebase_source : 464f1c553c7da25bec600af47dcbf502f967e8a9
tests: unify test-help

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rename : tests/test-help => tests/test-help.t
extra : rebase_source : 33590f99298bf21e9304635617a3bf4af468803c
tests: unify test-conflict-1

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rename : tests/test-conflict-1 => tests/test-conflict-1.t
extra : rebase_source : aababbdd46e20d86b83ab228a7ddc35c8cb065fb
tests: unify test-conflict-2

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rename : tests/test-conflict-2 => tests/test-conflict-2.t
extra : rebase_source : 5e82027c36d399a43ab3f4bc8b3d594cf0ca3d12
tests: unify test-convergedmerge

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rename : tests/test-convergedmerge => tests/test-convergedmerge.t
extra : rebase_source : 3ffe387c50c6395771399e89688f25450f443f0c
tests: unify test-empty-working-tree

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rename : tests/test-empty-working-tree => tests/test-empty-working-tree.t
extra : rebase_source : 777acbeb13c41e686cbcc6a5b246594098932761
tests: unify test-file-removal

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rename : tests/test-file-removal => tests/test-file-removal.t
extra : rebase_source : a0caa59ac10fd26d786bc609ea324d277e403338
tests: unify test-git-clone

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rename : tests/test-git-clone => tests/test-git-clone.t
extra : rebase_source : dc0d3fb98999ef2723cb4917c267566e6037577b
tests: unify test-git-submodules

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rename : tests/test-git-submodules => tests/test-git-submodules.t
extra : rebase_source : d5ea828b387ca677ae61a79fe69a549b82fb019c
tests: unify test-git-tags

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rename : tests/test-git-tags => tests/test-git-tags.t
extra : rebase_source : 0f98f00d50049d766f71bbee260f366dc0ceea0c
tests: unify test-git-workflow

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rename : tests/test-git-workflow => tests/test-git-workflow.t
extra : rebase_source : 796cadca3b6feb430f3fc605ec28160a5fbb39e8
tests: unify test-hg-author

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rename : tests/test-hg-author => tests/test-hg-author.t
extra : rebase_source : c78bb408356e0b2847dd6883ebf459b6a8833ea1