#### read rawdata timeseries (or DTi) & registration ####
-------------------------------------------
functs (left-click): read raw data
  read_regdat
  read_rawdata
-------------------------------------------

A default left-click on the "RD" button on the
"val3d:" entry line opens a pop-up to allow
reading a raw data BRIK ($rawdata, can select
from the "val3d:" dropdown, which contains all
BRIKs in current scandir), and a local
register.dat ($regdat).

This reads the data and registration into memory
buffers, so other functions (e.g., "V" on the
"val3d:" line, "T" and "S" on the "label:" line)
can do something with it.

Some examples of rawdata BRIKs include:

 (1) fMRI time-course series (typically short data)
 (2) 21-volume output of AFNI 3dDWItoDT (float data)

The startup values of $regdat and $rawdata will
typically be initialized by csurf.

If tksurfer is started using the csurf SURFACE
button on the main csurf panel, first use the
"session:" and "scandir:" dropdowns to pick the
desired scandir.

If tksurfer is started using the SURFACE-STATS
button from a SessionTools -> View Functional
Data panel, the initial $regdat and $rawdata will
come from the scandir in the current panel.

To reset the startup values of $regdat and
$rawdata in a tcl script, use "set" or "setfile"
(a globbing set), before calling the read
functions, for example:

  setfile regdat */some_scandir/register.dat
  read_regdat
  setfile rawdata */some_scandir/some_rawdata+orig.BRIK
  read_rawdata

where "*" is an abbreviation for the "image"
subdir of the current session.
