Phutaba report system

Adds a report system to Phutaba.

Users may select from a range of pre-defined reasons or write their own if enabled by the imageboard operator. Reports can be viewed as a table on the management panel, which is similar to the staff logs table. They can be filtered by age or 'cleared' status, and by default only the last 50 uncleared reports are shown. Apart from a reflink to the reported post, and the reason why it was reported, the reporter's IP is also displayed, so a ban can be applied in case of misuse.

Will most likely need to create the table manually, on an existing board (I had to).

CREATE TABLE `reports` (`timestamp` int DEFAULT NULL,`reporter` text,`board` text,`post` int DEFAULT NULL,`reason` text,`cleared` int DEFAULT NULL);