Create a grid layout for IGList

Summary:
Rebase from #140:

Create a flow layout for IGList that does not newline sections. Closes #3

- [x] Minimum inter-item spacing
- [x] Minimum line spacing
- [x] Constant item size with constant layout time
- [x] Update layout on insert/delete/move
- [x] Unit Test
Closes https://github.com/Instagram/IGListKit/pull/225

Differential Revision: D4211469

Pulled By: rnystrom

fbshipit-source-id: f4710dbf195701098ac50f94b6b2aa8c801b2a83

Examples/Examples-iOS/IGListKitExamples/SectionControllers/StoryboardLabelSectionController.swift

@@ -15,28 +15,35 @@
 import UIKit
 import IGListKit
 
+protocol StoryboardLabelSectionControllerDelegate: class {
+    func removeSectionControllerWantsRemoved(_ sectionController: StoryboardLabelSectionController)
+}
+
 final class StoryboardLabelSectionController: IGListSectionController, IGListSectionType {
     
-    var object: String?
+    var object: Person?
+    weak var delegate: StoryboardLabelSectionControllerDelegate?
     
     func numberOfItems() -> Int {
         return 1
     }
     
     func sizeForItem(at index: Int) -> CGSize {
-        return CGSize(width: collectionContext!.containerSize.width, height: 55)
+        return CGSize(width: (self.object?.name.characters.count)! * 7, height: (self.object?.name.characters.count)! * 7)
     }
     
     func cellForItem(at index: Int) -> UICollectionViewCell {
         let cell = collectionContext!.dequeueReusableCellFromStoryboard(withIdentifier: "cell", for: self, at: index) as! StoryboardCell
-        cell.textLabel.text = object
+        cell.textLabel.text = object?.name
         return cell
     }
     
     func didUpdate(to object: Any) {
-        self.object = object as? String
+        self.object = object as? Person
     }
     
-    func didSelectItem(at index: Int) {}
+    func didSelectItem(at index: Int) {
+        delegate?.removeSectionControllerWantsRemoved(self)
+    }
     
 }