Sub-bottom profiler depth plots

     Many sub-bottom profiler users want the data displayed in depth
rather than two-way travel time.  Sioseis process T2D transforms time
domain taces to depth domain traces using user defined velocity
functions.

Time domain plot from previous example (Healy06).
Depth domain plot of the same data.
stdout of t2d script.

Discussion of the chice of processing parameters
     The time domain sample interval is .5 milliseconds (500 microseconds).
86>lsd env-2006_226_0158_LF_028.sgy 1 2
      SHOT   TR       RP    TR ID  RANGE DELAY NSAMPS    SI   YR DAY HR MIN SEC
     25267     1       0     0  1      0  1066   5333    50 2006 226  1  58  39
     25268     1       0     0  1      0  1066   5333    50 2006 226  1  58  41
5333 samples at .00005 seconds is .2666 seconds

     Recall that the output units are kilometers.  OSI (output sample interval)
is preset to 1 meter or .001 kilometers.
      SHOT   TR       RP    TR ID  RANGE DELAY NSAMPS    SI   YR DAY HR MIN SEC
     27749     1       2     1  1      2   786    196  1000 2006 226  3   0   3
196 samples seems small, but plots with osi .5 and .25 look the same.