Support sqlite3 as a backend.

[skorokithakis]

Sqlite3 is a very capable database, which would work very well with Pushjet and make it much easier to install. Since Pushjet already uses SQLalchemy, there's no reason it couldn't easily support that backend. What's currently preventing sqlite3 from being used?

[skorokithakis]

It looks like the only thing preventing this is the database.sql file, which could presumably be written using the ORM instead, and would support any database backend SQLalchemy supports.

[Mechazawa]

SQLAlchemy supports SQLite but right now I'm using two MySQL specific datatypes. I'll remove those to make sure that the database back-end can be anything SQLAlchemy supports.

Example: https://github.com/Pushjet/Pushjet-Server-Api/blob/163c511226e82bd9a9fb54218e31cb8f28f1d4cc/models/message.py#L3

[skorokithakis]

That'd be great, thank you. For 99% of custom server deployments, SQLite will be ideal, since most people won't need to service many requests per second.

[Mechazawa]

I'll make custom deployments a lot less painful while I'm at it.