Better referential equality in useField

[Jephuff]

resolves #30 wraps onBlur, onChange, and onFocus in useCallback. wraps input in useMemo

[codecov[bot]]

Codecov Report

Merging #65 into master will not change coverage. The diff coverage is 100%.

@@          Coverage Diff          @@
##           master    #65   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           4      4           
  Lines          83     86    +3     
  Branches       17     17           
=====================================
+ Hits           83     86    +3

Impacted Files	Coverage Δ
src/useField.js	100% <100%> (ø)	:arrow_up:

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update f273d6b...f4e96ef. Read the comment docs.