"Raw" mode for BSAVE

[dansanderson]

It is possible to load a SEQ file without a PRG-like two-byte header by requesting that it be loaded into "raw" mode:

BLOAD "FNAME,S",P($1600),R

There ought to be a symmetric equivalent for BSAVE. Right now, BSAVE "FNAME,S" does create a SEQ file, but it always writes the start address. It accepts but silently ignores the ,R flag. This issue requests that BSAVE notice and respect the R flag, symmetrically with BLOAD:

BSAVE "FNAME,S",P($1600) TO P($160F),R

Alternatives considered
The ,S in the filename business is not the nicest, but it's traditional and would take more work to invent a new API that does the same thing. E.g. an ,S flag to the command could append ,S to the filename sent to the DOS and imply ,R automatically.