Adopted the alignTexts method to copy the SToken which do not have an
equivalent in the base text into the base text if a boolean flag is set
to true. If the base text is smaller than the text to merge, all token
which would not have a valid start and end value, are aligned either to
the start (if they occur left from the base text) or to the end (if they
occur after the end of the base text). The equivalence map then contains
the mapping from the original token to the copy, too. Currently, the
SAnnotations and SMetaAnnotations are moved. We need a copy method.