fix(annots): singleton-ness should be inerited

feat: make Builders, Patterns and various Annotation classes hashable

feat(builders): support deferrable functions and custom deferred repr

fix(patterns): fix pattern creation from Any typehint on python 3.10

feat(builders): expose resolve() and support custom deferred repr

feat(builders): support coercion from Builder and Deferred instances

fix(annots): must consider other base classes for abstractmethod impl…

…ementations (#26)

fix(annots): do not erase `__annotations__` classvar (#25)

fix(annotable): remove unfinished `__coerce__` implementation and add…

… tests (#24)

docs: add more pattern matching examples to the readme (#21)