New methods from bot api v3.5

Collect all api helper-methods in Client::ApiHelper module.
Add bin/fetch-telegram-methods to update methods list from website.

lib/telegram/bot/client/api_helper.rb

@@ -0,0 +1,31 @@
+require 'active_support/core_ext/string/inflections'
+
+module Telegram
+  module Bot
+    class Client
+      module ApiHelper
+        METHODS_LIST_FILE = File.expand_path('../api_methods.txt', __FILE__)
+
+        class << self
+          def methods_list(file = METHODS_LIST_FILE)
+            File.read(file).lines.
+              map(&:strip).
+              reject { |x| x.empty? || x.start_with?('#') }
+          end
+
+          # Defines method with underscored name to post to specific endpoint:
+          #
+          #   define_method :getMe
+          #   # defines #get_me
+          def define_helpers(*list)
+            list.map(&:to_s).each do |method|
+              define_method(method.underscore) { |*args| request(method, *args) }
+            end
+          end
+        end
+
+        define_helpers(*methods_list)
+      end
+    end
+  end
+end