Added missing 'public' access level
Added missing 'public' access level

Although those properties were marked `@IBInspectable` they lacked the `public` keyword, meaning they defaulted to `internal`. 

```swift
	koyomi.cellSpace = 1 // 'cellSpace' is inaccessible due to 'internal' protection level
	koyomi.sectionSpace = 1 // 'sectionSpace' is inaccessible due to 'internal' protection level
	koyomi.weekCellHeight = 25 // 'weekCellHeight' is inaccessible due to 'internal' protection level
```

As a result these properties could be set with interface builder. But *only* with interface builder.
shoheiyokoyama/Koyomi,shoheiyokoyama/Koyomi