Fix some errors in phpdocs.

Backported from 25cd430 (master).
Add a note about missing break in switch statement.

[ci skip]
Remove erroneous duplication of INFO in Redis profiles.

This oversight didn't end up in a blatant bug only because the correct
handler definition for INFO replaced the old class in the profile.

Backported from 5065541 (master).
Make PhpiredisConnection::getAddress() static and protected.

This method is mostly an utility method which is the main reason for
it bein static, but can be useful to have it available when extending
this class.

This change was inspired by b9b899e (master) even though the original
commit is meant to fix an issue not affecting v0.8.
Make Pipeline::executeCommand() return $this for fluent interface.

Backported from 3befbb3 (master).
Fix phpdocs for fluent interfaces.

Backported from a092f6d (master).

[ci skip]
[tests] No need to reassign $exception.

Backported from 728d9dc (master).
[tests] Fix a couple of glitches in our base PHPUnit classes.
Apply more phpdoc fixes.

Backported from 6a577a0 (master).
[tests] Fix a couple of innocuous glitches.
[tests] Remove unused "use" directive.
Remove useless return statement.

Backported from da8a203 (master).
Explicitly return null value.
Run php-cs against source code.
Merge branch 'v0.8-backport-fixes' into v0.8
Apply some more minor phpdoc fixes.