F8975 WIP: Previously the notation mode was not set correctly because...

F8975 WIP: Previously the notation mode was not set correctly because statements such as 'form={{form:SE}}' were not considered while determining the first token. This should now be fixed. The first token gets determined earlier on while joining the lines. Based on this first token the notation mode will be set like before. Added an error "Invalid level detected" which tells the user that an alias was used where it is not allowed. refs #8975