replace unicode arrows

* ⇒, →, ←
* because we don't want to show them in documentation snippets and
  then it's complicated to avoid that when snippets are
  located in src/test/scala in individual modules
* dont replace object `→` in FSM.scala and PersistentFSM.scala

project/TestExtras.scala

@@ -34,7 +34,7 @@ object TestExtras {
         onlyTestTags := Params.testTagsOnly,
 
         // add filters for tests excluded by name
-        testOptions in Test ++= excludeTestNames.value.toSeq.map(exclude ⇒ Tests.Filter(test ⇒ !test.contains(exclude))),
+        testOptions in Test ++= excludeTestNames.value.toSeq.map(exclude => Tests.Filter(test => !test.contains(exclude))),
 
         // add arguments for tests excluded by tag
         testOptions in Test ++= {