Extension in paste url does not get used

[enchant97]

When using a custom extension in the paste url e.g. example.com/2fCj3W3QOQ.py the original set lexer gets used instead.

This is due to how the cache works. Once a rendered paste is cached it will use it every time, even if a override lexer name is given.

Fix for V1.6.x

This will be fixed with only caching original set lexer, every time a override lexer is given it will not use the cache. In V1.7 it is planned to have a much better caching & storage system.