Calendar updates and webmaster email link

Calendar:
- calendar on main page now pulls data from the Google Calendar
specified in inc/calendar.php
- added class structure to inc/calendar.php to make it easier to use
its functions

Webmaster email link:
- added link to footer and styling
- footer items are better formatted on mobile devices (elements on new
line and dot separators disappear)

Error reporting:
- added to number of error types reported
- created error page to contain a page in question so we can see errors
without having to change config files on our MAMP servers. Otherwise,
blank white page appears with no errors, which isn’t that helpful.