Set version to 4.1.0

Author: lorentey

BTree.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |spec|
     spec.name         = 'BTree'
-    spec.version      = '4.0.2'
+    spec.version      = '4.1.0'
     spec.osx.deployment_target = "10.9"
     spec.ios.deployment_target = "8.0"
     spec.tvos.deployment_target = "9.0"

README.md

@@ -71,7 +71,7 @@ better with these than standard collections; continue reading to find out why!)
 [SortedBag]: http://attaswift.github.io/BTree/api/Structs/SortedBag.html
 [multiset]: https://en.wikipedia.org/wiki/Set_(abstract_data_type)#Multiset
 
-The latest version of `BTree` requires Swift 3.0. (The last release supporting Swift 2 was 2.1.0.)
+The latest version of `BTree` requires Swift 4. (The last release supporting Swift 3 was 4.0.2.)
 
 ### <a name="api">[Reference Documentation][doc]</a>
 

version.xcconfig

@@ -1,5 +1,5 @@
 // Increment the build number whenever you modify the version string.
-VERSION_STRING = 5.0.0-alpha
-BUILD_NUMBER = 12
+VERSION_STRING = 4.1.0
+BUILD_NUMBER = 13
 
 BUNDLE_IDENTIFIER_BASE = org.attaswift.$(PROJECT_NAME)