Downgrade EpwFile error to warning

The EpwFile parser was rejecting some TMY data sets that look
like AMY datasets because the header start day of the week
wasn't matching the actual start day of the week. This commit
downgrades the error to a warning and will treat such files as
TMY-type data.

[#70052720]
Address minutes parsing in EpwFile

This commit changes how the minutes field is being handled. It is
no longer read and the number of records per hour is used to compute
the minutes value. I've never actually seen a weather file with
anything other than hourly data, do I don't have any files to test that
this works for anything but recordsPerHour=1. To make this all work
smoothly, I have removed the m_timeStep member from EpwFile and
the time step getter method now returns a value computed  from a new
m_recordsPerHour member.

[#70052720]