Updater rework

[Groruk]

Description

• Reworked updater to use a new Updater class.
• Fixed template issues
• All Updates now use PDO instead of ADODB
• Charset is now passed as parameter for Database class
• Removed update support for SourceBans RC versions

[Bara]

Any reason why you set the default charset to utf8 but here https://github.com/sbpp/sourcebans-pp/pull/458/files#diff-8bdf163b47c46dcc7485c0e0a0370224R15 to utf8mb4? It's a bit confusing

[Groruk]

All update files are for older SourceBans or SourceBans++ versions to update (utf8mb4 support was officially added in 1.6.0 (update file 600)) so every update before that will still be utf8 (just for compatibility reason).