Add file summaries, @copyright tags and other comments. Covers majority
of the PHP code base now. I have avoided being too verbose and omitted
some potential tags.

Most visibly to the user, this comments every user configurable setting
and clarifies what some of the options do.

POMF_DB_USER and POMF_DB_PASS are not rendered perfectly in
phpDocumentor version 2.8.5. This is a sacrifice I made in attempt for
not being too verbose and obvious.

Response class gets a @todo for being a god object.

Interestingly, static/classes/UploadedFile.class.php is not licensed
under Expat license. Because it was posted in PHP.net comments, I
believe it's under the PHP license.

PSR-2 [1] is a highly regarded style guide in the PHP community
according to Stack Overflow [2].

The indentation was out of place in the source code. I've seen a
combination of 1 space tabs, 3 space tabs, 4 space tabs and 5 space
tabs. Some closing braces on the same line and a lot of the code
(especially moe code) had reached the point of losing readability.

Converted with php-cs-fixer and some hand adjustment.

[1]: http://www.php-fig.org/psr/psr-2/
[2]: https://stackoverflow.com/questions/3638083/list-of-highly-regarded
-php-style-guides

DATABASE UPDATE: `orginalname` renamed to `originalname` (run update.sql to update `files` table).
Run `update.sql` to update your database, no data will be lost (if you don't update it, pomf won't work properly).

`schema.sql`
- `id`s are now unsigned to double the maximum number of supported indexes
- `size` and `user` columns are unsigned too (we can't have a negative file size or a negative user id)

`static/classes/Response.class.php`
New class to manage responses and errors. Using a class for responses makes the code cleaner and easier to add new response type handlers in the future.
- The response type is declared while a new variable is initialized and the `error` and `send` methods will print a proper output according to it
- The header for the response is also set accordingly to the response type (`text/plain` for `csv`/`gyazo` output, `application/json` for `json` output)

`static/classes/UploadException.class.php`
`Exception` class extension to manage errors that may have occurred while uploading files to the server. This way every error is reported in detail.

`static/includes/settings.inc.php`
- `POMF_URL`: add an option to set the domain of the url to prepend to the newly generated filename (before it was hardcoded and it was `http://a.pomf.se/`) [this option is currently used only when the output is set to `gyazo`]

`upload.php`
- Add functions calls at the beginning to enable the output compression if possible (gzipped output)
- Include new classes
- `generate_name ()`
--- The new name generation algorithm is basically the same of the old one, but it's easier to add/remove characters if needed (eg. lower-case letters isn't enough and you need to add capital-case letters or digits)
--- Check directly the database instead of the filesystem to see if a generated filename is already in use
- `upload_file ()`
--- File errors generate a `UploadException` instead of a normal `Exception`
--- Move common code outside the `if` to avoid useless code repetition (only the query is now inside the condition)
--- Change file permissions of a file after moving it to the new directory (if the user didn't set a mask previouly these files wouldn't be world readable, we make sure they are)
- `diverse_array ()`
--- Function to reorder initial `$_FILES` array (easier to handle for `refiles`)
- `refiles ()`
--- Use a `foreach` cicle instead of a `for` one, easier to understand
- Create a new response object and set its response type (`csv`, `gyazo` or default to `json`)
- Edit response handling according to the new response class