if we're using multiple source datasteps (in which case tfrac = realtime mod 1.0).
Check that the original realtime matches too.

(time - highest_integer_time).  Use step 0 for times < 0,
and highest-available timestep when out of range > 0.

as listed in galaxyorbit.h.  New "-galaxy <first-galaxyorbit-coef>" option
enables it.  It compiles, but probably doesn't work yet.

in standalone ("warpsdb") mode.

Handle -seconds and -frames correctly -- thanks to g++ -Wall for catching
improper ref to ws->...!

attributes 0 1 2 ...  even though they aren't stored that way.

Use warp_invalidate() when conditions change.

Works but no -ref yet.

Add new SUBSTITUTE warp-type ("-subst field0"), which maps
three successive fields -> XYZ position (time-independent).

Where appropriate, update references to geomview license too,
now called COPYING.geomview.

(1 = scale, 6 = virdir tx ty tz rx ry rz, 7 = same plus scale, 9 = 3x3.)

Once we pick a license this might change, but
in the mean time, at least the NCSA UIUC origin is noted.

dvmmul -- don't use entry [3] of a 3-component point!

for performance etc. tests.