Style issues, failing sqlite tests, testuites with "," (#347)

[paslandau]

Fixes style issues. Adds markTestSkipped to SqlRunner tests if pdo_sqlite is missing.

Enables splitting --testsuite option by ,. GH issue: #347

• includes composer scripts to easily run test / style checks:

root@db51901fe7a6:/codebase/paratest# composer run-script -l
scripts:
  style            Runs the style script as defined in composer.json.
  style-fix        Runs the style-fix script as defined in composer.json.
  test             Run all tests
  test-unit        Run only unit tests
  test-functional  Run only functional tests

• updates readme
• adds changes from Change default console argument to auto #345 (with fixed tests)

[andreasschroth]

Thank you for your work, looks good. 👍 I only think it would have been better if the style issue fixes had been an own PR.