Stepped Daily, Monthly, and Yearly cycling tests:

Cycler(<anchor>,<step>)

Each test suite defines a single task on a 3-unit cycle:

Daily(20100110,3): 20100110, 20100113, 20100116, ...
Monthly(201001,3): 201001,   201004,   201007,   ...
Yearly(2010,3)   : 2010,     2013,     2016,     ...

The reference log is for a test run starting one unit in from the anchor
cycle time. Cylc should get exactly the same result for test runs that
start one, two, or three units in because the initial cycle point gets
adjusted up to the next on-sequence cycle time, so additional tests are
done to confirm this - by modifying the test start time in the installed
reference log on the fly.
