Implemented new escape class 'mysql' (realEscapeString).

Implemented defaultEscapeType. configurable via config.qfq.ini (global) and per Form.
Implemented max GET parameter lenght. Default: 50. BTW: in phpunit test there have been a parameter 'file' which exceeds the limit of 32.

Config.qfq: Skip empty variable names - happens in phpunit tests. Read new `systemEscapeTypeDefault`.
Constants.php: renamed  TOKEN_LDAP_ESCAPE_* to TOKEN_ESCAPE_LDAP_*. Add TOKEN_ESCAPE_MYSQL, TOKEN_ESCAPE_NONE
Database.php: Set charset to real_escape_string() functions properly. Proxy for mysqli::real_escape_string()
Evaluate.php: Respect global escapeTypeDefault. Implement
formEditor.sql: add column `escapeTypeDefault`. Add FormElement 'escapeTypeDefault'.