Create library with cross-platform sights

[abcdw]

About sights: https://github.com/HealthSamurai/ironhide#sight

Gather a list of frequently used sights: :ihs/str<->vector, :ihs/read-only, etc.

The implementation must work for both clojure and clojurescript, be tested and documented.

Maybe can be done as a separate library (discussable).