require ChannelOptions to be Equatable

Motivation:

ChannelOptions should've always been Equatable and so far we've hacked
around them not being Equatable when we wanted to compare them.

Modifications:

make all ChannelOptions Equtable

Result:

- ChannelOption comparison actually works
- fixes apple#598
- make more ChannelOptions stuff inlinable to not regress allocations

Sources/NIO/ChannelOption.swift

@@ -45,6 +45,13 @@ public struct SocketOption: ChannelOption, Equatable {
         self.level = level
         self.name = name
     }
+
+    public static func == (lhs: SocketOption, rhs: SocketOption) -> Bool {
+        switch (lhs, rhs) {
+        case (.const(let lLevel, let lName), .const(let rLevel, let rName)):
+            return lLevel == rLevel && lName == rName
+        }
+    }
 }
 
 /// `AllocatorOption` allows to specify the `ByteBufferAllocator` to use.

docs/public-api-changes-NIO1-to-NIO2.md

@@ -63,3 +63,4 @@
 - change `ChannelPipeline.addHandler[s](_:first:)` to  `ChannelPipeline.addHandler(_:postion:)` where `position` can be `.first`, `.last`, `.before(ChannelHandler)`, and `.after(ChannelHandler)`
 - change  `ChannelPipeline.addHandler(_:before:)` to  `ChannelPipeline.addHandler(_:postion:)` where `position` can be `.first`, `.last`, `.before(ChannelHandler)`, and `.after(ChannelHandler)`
 - change  `ChannelPipeline.addHandler(_:after:)` to  `ChannelPipeline.addHandler(_:postion:)` where `position` can be `.first`, `.last`, `.before(ChannelHandler)`, and `.after(ChannelHandler)`
+- all `ChannelOption`s are now required to be  `Equatable`