Stop using deprecated "json_array" type

fixed array declarations inside tools directory

AbstractMySQLDriver - Map 1429 to ConnectionException

Since it was deprecated.

Use short array declarations

fixed array declarations inside Query directory

Fix exception reference in documentation

Fixes #2760

Fix date interval database value truncation (string overflow)

Add mysql versions 5.6 and 5.7 to travis-ci

Fixes #2755
Fixes #2757

Fix documentation format regarding retryable exceptions

Add documentation regarding transactional exceptions

Move coverage session to sqlite.travis.xml file

Generate code coverage via phpunit

Add scrutinizer to the CI

Close #2730

Require PHP 7.1

Connection: Support IS NULL in update/delete criteria

If you pass a null to the where array of update or delete it's
pretty obvious what you want.

Most (all?) databases won't match anything if you actually try
to compare with NULL making this a silent failure without it.

fixed array declarations