Routr

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* use ``schemify`` for schema validation

* remove ``routr.schema`` completely

* remove ``routr.schema2`` -- ``qs`` and ``form`` guards are now can be imported directly
from ``routr`` module

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* routr.schema2: opt now can provide default value

* routr.schema2: allow namedtuple-based schemas

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* HTTP methods constants now can be used to define routes

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* allow setting custom class for URL matching -- use ``url_pattern_cls`` keyword
argument for ``route`` directive

* lightweight schema validation package ``routr.schema2``

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* URL pattern type ``str`` now has ``re`` arg -- allows to validate string via
regexp

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* fix url pattern matching for labels with numbers, like ``/{id1}``