Split in multiple packages

[tkrotoff]

Instead of
import { ... } from 'react-form-with-constraints/lib/Native'
import { ... } from 'react-form-with-constraints/lib/Bootstrap4'

Introduce multiple npm packages:

• react-form-with-constraints
• react-form-with-constraints-dom
• react-form-with-constraints-native
• react-form-with-constraints-bootstrap4

Will also solve some TypeScript typings:

node_modules/@types/node/index.d.ts(117,13): error TS2300: Duplicate identifier 'require'.
node_modules/@types/react-native/index.d.ts(8584,14): error TS2300: Duplicate identifier 'require'.

See DefinitelyTyped/DefinitelyTyped#16825

error TS2415: Class 'FormWithConstraints' incorrectly extends base class 'FormWithConstraints'.
  Types of property 'validateFields' are incompatible.

[tkrotoff]

Problem with react-native, see yarnpkg/yarn#3882

[tkrotoff]

See c28d123