Vanilla: version 2.1a40.
Merge branch 'master' into release/2.2

Conflicts:
	index.php
Add compatibility functions for next-gen code style.
Fix comment on new paths() function
paths() needs an explicit delimiter now.
Disallow object and embed tags; adds YouTube backward compat workaround
Add Vimeo backwards compat for no object tags
A few tweaks to the search model.
MarkString(), SearchExcerpt():
- Add some protection against marking a string with no terms.
Make Gdn_DirtyCache at least cache results in memory to reduce some db hits.
Tweak to search results.
Fix typo in VanillaSearchModel.
Remove the spam count popin from the dashboard.
Fix email confirm on new installs.
Make {activity_link} consistent with the other links.
Increase the size of reaction sprites to 16px;
Checkout {activity_link} from develop.
Add wraps to the discussions table head so that they can be targeted by css more easily.
Merge branch 'master' into release/2.2

Conflicts:
	applications/vanilla/views/discussions/table.php
	library/vendors/SmartyPlugins/function.activity_link.php
Hide the category drop down if there is only one allowed category.