matlab: add inverted f-antenna (ifa) example
matlab: fix ifa example
close file properly in h5readatt_octave

Signed-off-by: Thorsten Liebig <Thorsten.Liebig@gmx.de>
nf2ff: do check data ranges regardless if new or read only

Signed-off-by: Thorsten Liebig <Thorsten.Liebig@gmx.de>
tutorials: some minor updates

Signed-off-by: Thorsten Liebig <Thorsten.Liebig@gmx.de>