(deps): use PropTypes from prop-types lib instead of React

- fixes the React.PropTypes deprecation warning

Author: Fons Leenaars

package.json

@@ -41,6 +41,7 @@
     "webpack-dev-server": "^1.10.1"
   },
   "peerDependencies": {
+    "prop-types": "^15.5.8",
     "react": "^0.14.0 || ^15.0.0",
     "react-dom": "^0.14.0 || ^15.0.0"
   },

src/index.js

@@ -1,4 +1,5 @@
-import React, { Component, PropTypes } from 'react'
+import PropTypes from 'prop-types'
+import React, { Component } from 'react'
 import trimCanvas from 'trim-canvas'
 
 import Bezier from './bezier.js'