Add context object for render

Sources/HummingbirdMustache/Context.swift

@@ -0,0 +1,5 @@
+
+struct HBMustacheContext {
+    let first: Bool
+    let last: Bool
+}

Sources/HummingbirdMustache/Template+Render.swift

@@ -1,6 +1,6 @@
 
 extension HBMustacheTemplate {
-    public func render(_ object: Any, library: HBMustacheLibrary? = nil) -> String {
+    func render(_ object: Any, library: HBMustacheLibrary? = nil, context: HBMustacheContext? = nil) -> String {
         var string = ""
         for token in tokens {
             switch token {

Sources/HummingbirdMustache/Template.swift

@@ -8,6 +8,10 @@ public class HBMustacheTemplate {
         self.tokens = tokens
     }
     
+    public func render(_ object: Any, library: HBMustacheLibrary? = nil) -> String {
+        self.render(object, library: library, context: nil)
+    }
+    
     enum Token {
         case text(String)
         case variable(name: String, method: String? = nil)