Use ErrCorruptAttachPath in DefaultAttachmentStore.
Consider the possibility that the requested attachment doesn't have a file extension.
Rename variables to reduce boilerplate.
Add TestThaw.
Avoid an allocation in hookgen.
Add route_attach_start hook.
Add route_attach_post_get hook.
add topic_ogdesc_assign hook
initialise hooks after filling slices in bbcode init
hoist poll input checks out of inner loops in CreateTopicSubmit
shorten variable names and reduce boilerplate
