Fix PSR2 rules : "the static declaration should come after visibility"

Fix Shard Manager docs with more accurate docblocks in `SQLAzureShardManager` and `PoolingShardManager`

[TASK] Fix articles of words sounding with a consonant

Fix PSR2 rules : "As per PSR2, the static declaration should come after the visibility declaration."

Close #2794

#2794 allowing `DateTimeImmutable` instances when converting in mutable date types - reverts unintentional BC break

#2794 adding tests verifying the regression, `DateTimeImmutable` should STILL work, even if unintentionally

Add all missing MariaDb keywords to MySQL

this check does not make sense

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

As can be found in https://mariadb.com/kb/en/mariadb/reserved-words/.

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