Added sections tests. Allow for searching of context stack

Sources/HummingbirdMustache/Sequence.swift

@@ -2,37 +2,45 @@
 /// Protocol for objects that can be rendered as a sequence in Mustache
 public protocol HBMustacheSequence {
     /// Render section using template
-    func renderSection(with template: HBMustacheTemplate) -> String
+    func renderSection(with template: HBMustacheTemplate, stack: [Any]) -> String
     /// Render inverted section using template
-    func renderInvertedSection(with template: HBMustacheTemplate) -> String
+    func renderInvertedSection(with template: HBMustacheTemplate, stack: [Any]) -> String
 }
 
 public extension Sequence {
     /// Render section using template
-    func renderSection(with template: HBMustacheTemplate) -> String {
+    func renderSection(with template: HBMustacheTemplate, stack: [Any]) -> String {
         var string = ""
         var context = HBMustacheContext(first: true)
+
         var iterator = makeIterator()
         guard var currentObject = iterator.next() else { return "" }
 
         while let object = iterator.next() {
-            string += template.render(currentObject, context: context)
+            var stack = stack
+            stack.append(currentObject)
+            string += template.render(stack, context: context)
             currentObject = object
             context.first = false
             context.index += 1
         }
 
         context.last = true
-        string += template.render(currentObject, context: context)
+        var stack = stack
+        stack.append(currentObject)
+        string += template.render(stack, context: context)
 
         return string
     }
 
     /// Render inverted section using template
-    func renderInvertedSection(with template: HBMustacheTemplate) -> String {
+    func renderInvertedSection(with template: HBMustacheTemplate, stack: [Any]) -> String {
+        var stack = stack
+        stack.append(self)
+
         var iterator = makeIterator()
         if iterator.next() == nil {
-            return template.render(self)
+            return template.render(stack)
         }
         return ""
     }