Why is theme.inc looking for view template in calendar module
I cannot reproduce this myself but take a look at 

https://www.drupal.org/node/1091376 

It is an old ticket but is for the  7.x-2.x-dev branch and basicly it says disable your module remove the module directory and reinstall it so something like

Will disable the module.

 drush dis calendar


Will uninstall the module (if the module has a uninstall hook)

drush pmu calendar


Remove the directory

rm -rf __custom_path__/sites/all/modules/calendar


Most likely not necessary but wont hurt but will rebuild the registry and clear all cache

drush rr
drush cc all


Download the newest version of the module

drush dl calendar


And enable it.

drush en calendar


It should remove all traces of the old calendar and add a clean copy/install.

I would also do a drush updatedb just to double check if after all that everything is still in order.