Fixed the behaviour of the FMT tag, solving the problem occurred during bibreformatting.  Updated usage help string.  More of cosmetic readability updates.
Fixed the behaviour of the FMT tag, solving the problem occurred
during bibreformatting.  Updated usage help string.  More of cosmetic
readability updates.

inveniosoftware/invenio,tiborsimko/invenio,tiborsimko/invenio,inveniosoftware/invenio