Allow invokable classes as predicate (solves #270)

[heyphilllie]

This PR solves #270 . Predicates can now created from an invokable class. Like closures, the new predicates should directly added to the Select, Where or Update instance.

[mwillbanks]

@Ocramius the status of this one is hard... do we have someone willing to update this library for PHP 7? Or at a minimum get the travis and composer config moving in the right direction?

[Ocramius]

IMO we should hold back new features until 7.1 is the minimum version. Everything we add without explicit type declarations will just come back like a boomerang.

[ezimuel]

@Ocramius I tagged this as 3.0 release.

[baileylo]

@Ocramius I was wondering if you could go into detail how explicit type declarations would help in this situation or conversely if there is any foreseeable boomerang?

[weierophinney]

This repository has been moved to laminas/laminas-db. If you feel that this patch is still relevant, please re-open against that repository, and reference this issue. To re-open, we suggest the following workflow:

• Squash all commits in your branch (git rebase -i origin/{branch})
• Make a note of all changed files (`git diff --name-only origin/{branch}...HEAD
• Run the laminas/laminas-migration tool on the code.
• Clone laminas/laminas-db to another directory.
• Copy the files from the second bullet point to the clone of laminas/laminas-db.
• In your clone of laminas/laminas-db, commit the files, push to your fork, and open the new PR. We will be providing tooling via laminas/laminas-migration soon to help automate the process.

[michalbundyra]

This repository has been closed and moved to laminas/laminas-db; a new issue has been opened at https://github.com/laminas/laminas-db/issues/62.