Add Package.swift and move files around

Sources/Namespace.swift

@@ -0,0 +1,44 @@
+public class Namespace {
+  public typealias TagParser = (TokenParser, Token) throws -> NodeType
+
+  var tags = [String: TagParser]()
+  var filters = [String: Filter]()
+
+  public init() {
+    registerDefaultTags()
+    registerDefaultFilters()
+  }
+
+  private func registerDefaultTags() {
+    registerTag("for", parser: ForNode.parse)
+    registerTag("if", parser: IfNode.parse)
+    registerTag("ifnot", parser: IfNode.parse_ifnot)
+    registerTag("now", parser: NowNode.parse)
+    registerTag("include", parser: IncludeNode.parse)
+    registerTag("extends", parser: ExtendsNode.parse)
+    registerTag("block", parser: BlockNode.parse)
+  }
+
+  private func registerDefaultFilters() {
+    registerFilter("capitalize", filter: capitalise)
+    registerFilter("uppercase", filter: uppercase)
+    registerFilter("lowercase", filter: lowercase)
+  }
+
+  /// Registers a new template tag
+  public func registerTag(name: String, parser: TagParser) {
+    tags[name] = parser
+  }
+
+  /// Registers a simple template tag with a name and a handler
+  public func registerSimpleTag(name: String, handler: Context throws -> String) {
+    registerTag(name, parser: { parser, token in
+      return SimpleNode(handler: handler)
+    })
+  }
+
+  /// Registers a template filter with the given name
+  public func registerFilter(name: String, filter: Filter) {
+    filters[name] = filter
+  }
+}