Since extensions may add nested includes, we need to make sure they are eager-loaded to avoid excessive queries. For example, when the tags extension adds "tags" and "tags.state".
Laravel's `image` validation rule allows svg files to pass validation, but we can't handle svgs so it would result in an unspecified 500 error which isn't nice.
Closes#268. Not going to bother with a preview SVG or anything fancy for now – we can think about that as part of #746. Right now it's just good to finally get this functionality in!
Also need to think about apple-touch-icon, msTile stuff, and social sharing image. Not sure if this is all too much for core, but it's definitely too much for the current Appearance page layout. Again, something to think about as part of #746.
Code is a bit rough around the edges, but figured there's not much point in using the command bus properly since #870.
components/font-awesome is ~8 MB smaller than fortawesome/font-awesome because it excludes all examples/docs. Reducing dependency filesize will be important when we want to package up a .zip for distribution.
Extensions can add default column values in their migrations, but Eloquent doesn't know about this when it first saves a model to the database.
This is useful in flarum-ext-approval where the default value for is_approved on the posts table is true.
This helps to fix a bug in flarum-ext-tags where a user could not rename or edit the tags of their own discussion if it was in a restricted tag. This was due to the order of GetPermission event listeners – the logic that determines that a user *can't* perform an action because of a restrictive tag was running before (and thus instead of) the logic that determines that a user *can* edit their own stuff.
The solution is to change the "catch-all" methods on Policies to "after" instead of "before" – that is, they will run only if the per-ability methods return null.
We also simplify the GetPermission event by passing the model as a sole "argument", as I can't imagine any cases where we'll need more than one argument.
