Add an option to exclude certain GET variables in the language menu

Sometimes it is necessary to exclude certain GET variables from the generated language link. For example, there can be a parameter to the page, which makes sense only for the current language. Current implementation of the language menu viewhelper does not allow to exclude such variables.

Introduce a new viewhelper parameter named "excludeQueryVars" and use it to exclude parameters if necessary.

Please, note that existing "configuration" parameter cannot be used for this due to the way how variables are added to additionalParams now.