feat #1132 Add env. parameter for escapeforhtml

- added templateSettings in EnvironmentSettings
- added hasEscapeHtmlByDefault and setEscapeHtmlByDefault to Environment
- modified Statements.js to check this parameter
- added tests

! I still need to update ExpressionEscapeTest , but if someone can have a look and let me know if you're fine with the gist of the change that'd be great.