Remove local-only entries from hg ignore

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branch : py3
Adding support for themes

Starting with a bootstrap-based theme (next to a minimal one). More to
follow.

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extra : histedit_source : 4d9839909f32068cd5c4e394bb86a3831caf3805%2Ca03601b4a1ddfa30d9708420e3cfd846aca240b6
Update ignore file

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extra : histedit_source : fdd882be9cbce3f3dd185c752ccaf9ca7cf2cc4f%2C8c33f771f1b36d8babb3349343ba505716eb4e69
Use a more compact name (`hx`) for the HTML escaping utility function.

However, the old one (`htmlspecialchars`) is still available.
Use new escape function in bootstrap theme
Add new theme: foundation
Fix typo in bootstrap theme
Add note about new themes feature to README
Update tests to latest changes
Merge in default

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branch : py3