Fixed using spaces in filter expressions and variables lists (#178)

* fixed using spaces in filter expression

* fixed breaking variables lists and filters by spaces

* simplified smartJoin

* avoid force unwrap

Sources/Variable.swift

@@ -209,11 +209,11 @@ extension Dictionary : Normalizable {
 
 func parseFilterComponents(token: String) -> (String, [Variable]) {
   var components = token.smartSplit(separator: ":")
-  let name = components.removeFirst()
+  let name = components.removeFirst().trim(character: " ")
   let variables = components
     .joined(separator: ":")
     .smartSplit(separator: ",")
-    .map { Variable($0) }
+    .map { Variable($0.trim(character: " ")) }
   return (name, variables)
 }