Add proximity filter ~=

[mkobel]

Implement proximity filter to allow to create criteria queries like where("cn").proximity("John") resulting in a filter like (cn~=John)

[jzheaux]

Thanks for the PR, @mkobel! I appreciate this idea; I've left the rest of my feedback inline.

[mkobel]

Thanks for the PR, @mkobel! I appreciate this idea; I've left the rest of my feedback inline.

@jzheaux Thank you for the feedback. I rebased the changes. I hope they are as expected.

[jzheaux]

@mkobel, thanks for the quick turnaround! Will you please do the following two polishes to wrap up:

1. To your JavaDoc, add @since 3.3 to any new public methods or classes
2. Locally run ./gradlew format && ./gradlew check

[mkobel]

@mkobel, thanks for the quick turnaround! Will you please do the following two polishes to wrap up:

1. To your JavaDoc, add @since 3.3 to any new public methods or classes
2. Locally run ./gradlew format && ./gradlew check

@jzheaux Thank you for the feedback.
Sorry, I missed the tests after the last change. I now had to remove the equals test in ProximityFilterTests as the EqualsTester requires a subclass, which is not possible due to the final ProximityFilter. I hope this OK for you.

[jzheaux]

Thanks, @mkobel! I'll see about adding some additional tests in a polish commit.