white space nits
Constify the vfp structs
Move some non-protocol specific body-fetch code back to cache_fetch.c
Fix an oversight when we closed #942:  The exact same condition
can happen if we gunzip on fetch.
De-fluff
Eliminate BS_ZERO, it's same as BS_NONE.

Explicitly set BS_NONE for synth 503.
Shuffle more stuff between proto-specific and generic fetch code.