Perf: Enable cache, fix value casting for MySQL and MariaDB and add plugin for Engine creation

[adrien-berchet]

Description

Fixes #436
Cache could not be enabled because of conversion performed in compilation step. Now this conversion is performed during the before_cursor_execute event.
A SQLAlchemy plugin was created for the sqlalchemy.Engine objects in order to automatically attach the relevant events based on the dialect of the Engine.

Checklist

This pull request is:

• A documentation / typographical error fix
  • Good to go, no issue or tests are needed
• A short code fix
  • Please include: Fixes: #<issue number> in the description if it solves an existing issue
    (which must include a complete example of the issue).
  • Please include tests that fail with the main branch and pass with the provided fix.
• A new feature implementation or update an existing feature
  • Please include: Fixes: #<issue number> in the description if it solves an existing issue
    (which must include a complete example of the feature).
  • Please include tests that cover every lines of the new/updated feature.
  • Please update the documentation to describe the new/updated feature.

[adrien-berchet]

To make things simpler we should add a general function like enable_geoalchemy(engine) that would listen for proper events depending on the dialect of the engine.

[adrien-berchet]

To make things simpler we should add a general function like enable_geoalchemy(engine) that would listen for proper events depending on the dialect of the engine.

This was made using a plugin for Engine objects.

[calebj]

See ec72f5f for my proposed changes

[adrien-berchet]

See ec72f5f for my proposed changes

I updated according to your suggestion. I added two parameters, one for MySQL and one for MariaDB, just in case some drivers for MariaDB change their behavior.
Does it look good to you now?

[calebj]

Good idea, looks good to me.

[adrien-berchet]

Great!
Thank you very much for all of this, this is a great improvement for GeoAlchemy2! ❤️