-Updated modelsim_regression_test_vhdl.py to append more useful information to

 the log file using the 'Email' tags. Log file now contains lists of passed
 and failed test benches.
-Added modelsim_regression_test_vhdl_cron.sh which is to be executed as a Cron 
 job.
 . modelsim_regression_test_vhdl_mail.sh (newly added) is called to send  
   result mail.