Different storage location for development environment

[DylanDevelops]

The feature request

When building locally while developing, it is possible to accidentally corrupt your real tmpo.db file.

Proposed solution

It would be nice to have an alternative storage location for locally built tmpo binaries while developing, other than ~/.tmpo/tmpo.db, so that real entries don't get corrupted during testing.

This is also useful for testing new features, as the DB might not be formatted the same if it changes in the future.

Additional context

No response

[DylanDevelops]

While this issue is closed for now, it may come up later as mentioned in my #39 (comment) on the PR.

I think this should be helpful; however, I would have liked development environments to use the development directory by default. I may switch this to an "opt-out" system later on.

To make the switch from opt-in to opt-out, I just need to include steps to set TMPO_DEV=0 when building from source for local production purposes.