feat(shape): add rotate manipulation property

Closes #60.

README.md

@@ -415,6 +415,8 @@ The functions are defined as the following properties.
 - `reverse` is a *boolean* that when:
   - `true` reverses the order of points
   - `false` has no effect
+= `rotate` is a *number* that defines the degrees to rotate the
+  shape clockwise
 - `scale` is either:
   - a *number* that defines the scale factor, or
   - an *array* that includes:

examples/fill-rule/client.js

@@ -4,6 +4,7 @@ const from1 = {
   type: 'path',
   d: 'M20,20H80V80H20ZM30,30V70H70ZM40,40H60V60H40Z',
   fillRule: 'evenodd',
+  rotate: 45
 }
 
 const from2 = {

src/core/shape/create.js

@@ -23,6 +23,7 @@
  *
  * @property {integer} [moveIndex] - the amount of points by which to offset a shape's index point.
  * @property {number[]} [offset] - the amount to offset a shape's points horizontally and vertically.
+ * @property {number} [rotate] - the clockwise angle to rotate the shape.
  * @property {boolean} [reverse] - reverses the shape's points.
  * @property {(number|(number|string)[])} [scale] - scales a shape.
  */
@@ -134,7 +135,7 @@ import {
 } from './props'
 
 import { filter } from '../helpers'
-import { moveIndex, offset, reverse, scale } from 'points'
+import { moveIndex, offset, reverse, rotate, scale } from 'points'
 import { toPoints } from 'svg-points'
 
 /**
@@ -267,6 +268,9 @@ const manipulate = ({ manipulations, points }) => (
 
         break
 
+      case 'rotate':
+        return rotate(nextPoints, args)
+
       case 'scale':
         const isArray = Array.isArray(args)
         const scaleFactor = isArray ? args[ 0 ] : args

src/core/shape/props.js

@@ -18,6 +18,7 @@ const manipulationProps = [
   'moveIndex',
   'offset',
   'reverse',
+  'rotate',
   'scale'
 ]
 

tests/core/shape/create.js

@@ -375,6 +375,28 @@ describe('manipulate', () => {
     expect(manipulate({ manipulations, points })).toEqual(result)
   })
 
+  it('should rotate points', () => {
+    const manipulations = { rotate: 90 }
+
+    const points = [
+      { x: 0, y: 0, moveTo: true },
+      { x: 100, y: 0 },
+      { x: 100, y: 100 },
+      { x: 0, y: 100 },
+      { x: 0, y: 0 }
+    ]
+
+    const result = [
+      { x: 100, y: 0, moveTo: true },
+      { x: 100, y: 100 },
+      { x: 0, y: 100 },
+      { x: 0, y: 0 },
+      { x: 100, y: 0 }
+    ]
+
+    expect(manipulate({ manipulations, points })).toEqual(result)
+  })
+
   it('should scale points', () => {
     const manipulations = { scale: 2 }