Dqpy

A change introduced in 2.0 was that a SQLAlchemy session is closed after its objects are committed. This made the objects not available for later use, and is almost certainly not desirable. This patch reverts the change.

Note that a session should eventually be closed. In Flask, a session can be closed by being removed when an HTTP request finishes. In other scenarios, remember to close session where appropriate.

The primary feature of this release is a JSON and Redis backed cache module that replaces the old, ORM-based caching mechanism. The old code was never intended for production use and has been removed.

This release adds a few file system related functions such as `rmrf` and `mkdirp`.

There's no version 1.3 - the functions were originally part of the `dq.util` package in 1.3 but was moved to `dq.fsutil` package in 1.3.1.

This release adds a `safe_cast` helper for type conversion and a limit/offset helper for writing SQL queries.

Additionally, the `get_multi` function has been updated to return `limit` instead of `limit + 1` results when `limit` is specified. Callers that require pagination should get total count in a separate query instead of relying on one additional result being returned.

This release adds `dbadmin` console script to replace the usual `database.py` script.

* Create database: `dbadmin create [url config key]`
* Drop database: `dbadmin drop [url config key]`

The `mysql` config key is changed to `sql`, to be more generic. To enable MySQL-specific functions, a `flavor=mysql` entry needs to be added to the `sql` key.

Initial release.