Add a new MSSQL_USE_LEGACY_COLLATIONS option to have collations behave like in 7.x-1.x (to properly support 7.x-1.x to 7.x-2.x upgrades)

Add support for new configuration setting 'MSSQL_INSERT_DISABLE_OUTPUT' to prevent using OUTPUT in INSERT statements.

Remove unnecessary checks from status screen + not having wincache should be a warning not an error.

Use a simpler static caching strategy for escapeField() + remove the query cache (does not make a difference after upgrading to PHP7).