Simplify main_proc decorator and defining logging as print on the main thread.
Simplify main_proc decorator and defining logging as print on the main thread.

The print function from python3 is imported because in python2 the
"print" isn't a function.

mroyluna/summer17mantlesim,Johnson-A/mantle_simulation,mroyluna/summer17mantlesim,Johnson-A/UNM_Research,mroyluna/summer17mantlesim,Johnson-A/UNM_Research,Johnson-A/UNM_Research,Johnson-A/mantle_simulation