Added Integer.times

This method returns an Iterator that iterates from 0 up to the value of
the integer.

runtime/src/std/integer/extensions.inko

 # Extensions for the `Integer` type that can only be defined later on in the
 # bootstrapping process.
+import std::iterator::(Enumerator, Iterator)
 import std::process
 import std::string_buffer::StringBuffer
@@ -68,4 +69,18 @@ impl Integer {
     StringBuffer.from_array(characters).to_string
   }
+
+  # Returns an `Iterator` that iterates from `0` up to the value of `self`.
+  #
+  # # Examples
+  #
+  # Iterating from `0` to `10`:
+  #
+  #     4.times.to_array # => Array.new(0, 1, 2, 3)
+  def times -> Iterator!(Integer) {
+    let mut index = -1
+    let max = self - 1
+
+    Enumerator.new(while: { index < max }, yield: { index += 1 })
+  }
 }

runtime/tests/test/std/test_integer.inko

@@ -345,3 +345,11 @@ test.group('std::integer::Integer.format') do (g) {
     }
   }
 }
+
+test.group('std::ineger::Integer.times') do (g) {
+  g.test('Iterating from 0 up to the value of an Integer') {
+    let values = 4.times.to_array
+
+    assert.equal(values, Array.new(0, 1, 2, 3))
+  }
+}