Add `filter` aliases for `Enumerable` and `Hash`.

mrbgems/mruby-array-ext/mrblib/array.rb

@@ -955,4 +955,5 @@ class Array
 
   alias append push
   alias prepend unshift
+  alias filter! select!
 end

mrbgems/mruby-enum-ext/mrblib/enum.rb

@@ -826,4 +826,5 @@ module Enumerable
     end
     hash.values
   end
+  alias filter select
 end

mrbgems/mruby-hash-ext/mrblib/hash.rb

@@ -494,4 +494,7 @@ class Hash
       self.fetch(k, &block)
     end
   end
+
+  alias filter select
+  alias filter! select!
 end