Fix build for Swift 5.0.1

Sources/FirebladeECS/Component+Access.swift

@@ -5,6 +5,7 @@
 //  Created by Christian Treffs on 25.06.19.
 //
 
+#if swift(>=5.1)
 @dynamicMemberLookup
 public struct ReadableOnly<Comp> where Comp: Component {
     @usableFromInline let component: Comp
@@ -31,3 +32,4 @@ public struct Writable<Comp> where Comp: Component {
         nonmutating set { component[keyPath: keyPath] = newValue }
     }
 }
+#endif

Sources/FirebladeECS/Entity.swift

@@ -104,4 +104,9 @@ public struct Entity {
 }
 
 // MARK: - Equatable
-extension Entity: Equatable { }
+extension Entity: Equatable {
+    public static func == (lhs: Entity, rhs: Entity) -> Bool {
+        return lhs.nexus == rhs.nexus &&
+               lhs.identifier == rhs.identifier
+    }
+}

Sources/FirebladeECS/Family.swift

@@ -124,4 +124,9 @@ extension Family {
 extension Family.EntityComponentIterator: LazySequenceProtocol { }
 
 // MARK: - Equatable
-extension Family: Equatable { }
+extension Family: Equatable {
+    public static func == (lhs: Family<R>, rhs: Family<R>) -> Bool {
+        return lhs.nexus == rhs.nexus &&
+               lhs.traits == rhs.traits
+    }
+}

Tests/FirebladeECSTests/AccessTests.swift

@@ -10,7 +10,7 @@
 import FirebladeECS
 import XCTest
 
-
+#if swift(>=5.1)
 class AccessTests: XCTestCase {
 
     func testReadOnly() {
@@ -42,3 +42,4 @@ class AccessTests: XCTestCase {
 
     }
 }
+#endif