implementing the ability to show gregorian dates along with jalali dates in jcal output

[ashkang]

Possibly as a switch. Something like -S.
Bahman 1392
January/February 2014
Sh Ye Do Se Ch Pa Jo
1/21 2/22 3/23 4/24
5/25 6/26 7/27 8/28 9/29 10/30 11/31
12/1 13/2 14/3 15/4 16/5 17/6 18/7
19/8 20/9 21/10 22/11 23/12 24/13 25/14
26/15 27/16 28/17 29/18 30/19