Perform string comparison using hash_equals()

[Nightfirecat]

It's timing-safe, and generally a better alternative to ==/=== or strcmp() as a result.

Places where this needs to change:

• https://github.com/Nightfirecat/RealmEye-API/blob/master/items.php#L25
• https://github.com/Nightfirecat/RealmEye-API/blob/master/index.php#L45
• https://github.com/Nightfirecat/RealmEye-API/blob/master/index.php#L79 (and else if branches)
• https://github.com/Nightfirecat/RealmEye-API/blob/master/index.php#L80
• https://github.com/Nightfirecat/RealmEye-API/blob/master/index.php#L113
• https://github.com/Nightfirecat/RealmEye-API/blob/master/index.php#L124
• https://github.com/Nightfirecat/RealmEye-API/blob/master/index.php#L129
• https://github.com/Nightfirecat/RealmEye-API/blob/master/index.php#L148 (and else if branches)
• https://github.com/Nightfirecat/RealmEye-API/blob/master/index.php#L223
• https://github.com/Nightfirecat/RealmEye-API/blob/master/index.php#L241
• https://github.com/Nightfirecat/RealmEye-API/blob/master/index.php#L277
• https://github.com/Nightfirecat/RealmEye-API/blob/master/deploy.php#L23
• https://github.com/Nightfirecat/RealmEye-API/blob/master/deploy.php#L28

[Nightfirecat]

Given that the only 'sensitive' comparison is done in the deploy script, and it's already using hash_equals(), I'm inclined to say that the performance hit won't be worth it here. In general, most of the application doesn't have any security implications, so there's no real need for this.