Updated PHPStan to v0.11

Index length can be a `string`: ensure that it is an integer when read by the `MySqlSchemaManager`

Add column charset for MySQL

Consider column lengths when comparing indices

`CREATE_OPTIONS` is nullable in MySQL

Introduced a smoke testing phase on Travis to run SQLite tests and CS checks first

CI: Test against MySQL 8.0 on Travis

Removed unused build files

Travis CI: PHP 7.3 tests on MySQL 8.0

Link to Slack instead of Gitter

Gitter has been deprecated in favor of Slack for all Doctrine purposes.

fixed annotations of parameter $columns in Table

Grouped PHPStan and PHP_CodeSniffer for parallel execution

Fixed parsing MySQL create table flags (options without a value)

Fix Fetch mode query in MasterSlaveConnection

ResultCacheStatement lost its cache capability on fetchAll method

Fix: Ensuring correct ALTER TABLE statement for creation of an AUTO INCREMENT column as new PRIMARY KEY

Require PHP 7.2, drop <7.2 in Composer & on CI

[SQL Anywhere] Fix view schema introspection test

[SQL Anywhere] Fix fetching empty values via fetchAll()