Handle No-chars in text fields when reading and writing.

[Krolken]

A text data field that is not completely filled uses null-data \x00 to fill out the rest of the bytes.

When reading the data we would like to remove these as it makes it annoying to serialize. And when writing data back we would like to fill the not used space with null-data.

So unit m3 would be filled as `'m3\x00\x00\x00\x00\x00\x00' for example.

But there are some edge cases where there is data after null-data. See #1. Example would be
'Ext.power modem B6\x00o%} '
'Call window B2\x00 B2\x002\x00\x95\x02'
'Status St1\x00Closed\x00 '
'Flow Q\x00 B3} 3}!A} } } '
"Cover B1\x00\x00\x00\x00\x00\x04B\x00;\x00\x00'\x00J\x00"