Show no update nag upon initial activation of Largo

[benlk]

Changes

• Create new hook on after_switch_theme, the activation hook, that:
  • doesn't run if there is already saved theme options for any version of Largo
  • requires the default Largo options from options.php, which are otherwise not included in the theme outside of the options framework pages
  • runs the options framework initiation function
  • sets the defaults using Largo's function to do so
  • sets the version number to the current version
  • removes the update nag from its enqueued action, for the single page load where after_switch_theme runs, because at page generation time apparently the Largo version is not set in the database even though it is set during this function that appears to run before everything else on the page. (I checked with subsequent page reloads, and with some var_logging, and the variable is set on page reload but not yet on page load. 🙁 )
  • removes the theme options menu link hijacker from the menus, for the single page load where after_switch_theme runs, for the same reason
• if of_get_option is called in a situation where the database doesn't contain all the information it needs to work properly, it complains to the debug log.

Why

#690

[aschweigert]

This seems fine to me. I'd say we should clean up the updates file generally, but probably ok to leave as-is for now as long as it works.