Modification of savetrd 'name.trd','name.B'

[FasterHLM]

I request to modify the savetrd command when saving a BASIC file. In the current implementation, the BASIC file is written to the TRD disk exactly as long as specified in the savetrd command parameters. For example, if the BASIC file occupies 100 bytes, those 100 bytes will be written to the disk. In the original TR-DOS, the length is written in multiples of the sector size — 256 bytes. Therefore, when saving a BASIC file in TR-DOS, the disk will store the full 256 bytes (100 bytes of the BASIC program + the next 156 bytes from memory). It would be great if savetrd could implement the same logic. This rounding to 256 bytes was widely used for creating hidden messages inside BASIC loaders, where a text message would be placed in the remaining space at the end of the sector.