Implemented lambda::userDefined::detail::call_updateEnv.
Implemented lcpp::StackBase<>::pop(<relativeIndex>).
Added unittests for StackBase.
Implemented lcpp::cons::pushAllReverse.
Implemented call of user defined lambdas.
Implemented syntax 'begin'.
Fixed bug in syntax::builtin::checkArguments.
Syntax 'define' now gives the value its new name, if it is a nameable value.
Implemented simple unit test for 'define'.