ReactiveX/Rx.rb — pull request #32 by jca02266 (2014-12-20 14:06:28+00:00)
Title: Implement timer

Add Observable.timer to work below example:

```ruby
require 'rx'

source = RX::Observable.timer(0, 1)
.time_interval()
.map() {|x| x.value.to_s + ":" + x.interval.to_s }
.take(5)

subscription = source.subscribe(
lambda {|x|
puts 'Next: ' + x.to_s
},
lambda {|err|
puts 'Error: ' + err
},
lambda {
puts 'Completed'
})

sleep 5
# => Next: 0:0
# => Next: 1:1000
# => Next: 2:1000
# => Next: 3:1000
# => Next: 4:1000
# => Completed
```