New Smarty plugin: {categories_link}

{category_link} is already present but links to the currently active
category and not the category index.
Merge branch 'master' of github.com:vanillaforums/Garden
Make sure to serialize the row in DiscussionModel->Save().
Merge branch 'master' of github.com:vanillaforums/Garden
Merge branch 'master' into hotfix/2.1a37
Fix security hole allowing Format to be changed during edit.
Fix category subtree from hot fix.
Give missing category photos a hidden class.
Fix /entry/forgotpassword Remember link
Merge branch 'master' of github.com:vanillaforums/Garden
Increment to 2.1a38
Fix IP bug.
Merge branch 'master' of github.com:vanillaforums/Garden
Discussions sorting; WIP 1
Switch to json encoded update checks to prevent php object injection hacks.
Fix bug in UpdateModel::AnalyzeAddon() that caused addons generated with git archive to not be parsed.
Fix parse error in Skeleton app.
Merge branch 'master' into release/2.1b1

Conflicts:
	applications/vanilla/views/categories/helper_functions.php
	index.php
Give a bigger timeout to dba/counts.
Offer a bit of protection agains non-existent users in FormatString().