MS_SPLIT_TRACE - Apply splitting operator to a pair of orthogonal traces

[T00sp,T90sp] = MS_split_trace(time,T00,T90,fast,tlag)

Inputs:
   time (vector) : Series of time points where amplitudes are known (s)
   T00 (vector)  : Series of amplitudes of transverse wave #1 before
                   splitting applied.
   T90 (vector)  : Series of amplitudes of transverse wave #2 before
                   splitting applied.
   fast (scalar) : polarisation direction of fast wave (degrees)
   tlag (scalar) : lag time splitting operator to be applied (s)

Outputs:
   T00sp (vector)  : Series of amplitudes of transverse wave #1 after
                     splitting applied.
   T90sp (vector)  : Series of amplitudes of transverse wave #2 after
                     splitting applied.

MS_split_trace applies a shear wave splitting operator (fast and tlag)
to a time series of the amplitude of displacement in two orthogonal
directions (e.g. of waves or wavelets) stored in time, T00 and T90. The
displacements are first rotated into the fast direction before being time
shifted by forwards (for the fast wave) or backwards (for the slow wave)
by half of the lag time and interpolated onto the same time series. The
resulting displacements are then rotated back into the original frame.
The fast direction is measured clockwise from the direction of T00
with a 90 degree fast orientation being parallel with T90.