Fix error for velocity updates in elastic SH-waves

See merge request !5

Import seitosh

libstfinv now supports semicolons as an alternative to commas being used as field separators in parameter values.

See merge request !4

Merge branch 'master' into import_Seitosh

Merge branch 'vendor_Seitosh' into import_Seitosh

Drop current version of Seitosh code. The contents are taken vom branch master
of [Seitosh](https://git.scc.kit.edu/Seitosh/Seitosh). The current master
commit in Seitosh is 0cdd3c0568.

With this vendor drop libstfinv supports semicolons as an alternative to commas being used as field seperators in parameter values.

Commands executed in the root directory of IFOS2D:

    rm -rfv contrib/stfinv
    (cd ~/git/Seitosh/src/libs/libstfinv; tar cvf - $(git ls-files)) \
      | ( cd ~/git/IFOS2D/contrib; mkdir stfinv; cd stfinv; tar xvfps -)
    git add --force contrib/stfinv

Set STF_FULL to 1 in order to ignore the time window and use the total wavefield to invert for the source time function.

Will write filtered and windowed displacement seismograms to disk.

Import seitosh

@wittkamp @lgass @r 
[libstfinv](https://git.scc.kit.edu/Seitosh/Seitosh/tree/master/src/libs/libstfinv) in [Seitosh](https://git.scc.kit.edu/Seitosh/Seitosh) provides a new feature:

A new taper option for procedures operating in the Fourier domain is implemenetd in libstfinv. This can be used to remove unwanted acausal or coda components of the impulse response of the source time function correction filter. See usage information provided by libstfinv:

    A time domain taper can be applied to the impulse response of the correction
    filter by using option irtap. Four time values are given in units of seconds:
    t1, t2, t3, and t4. They must be in increasing order and (t4-t1) must be
    smaller than the total duration of the time series used to represent signals
    internally. Times value are allowed to be negative. Time series are understood
    to be periodic (due to discrete Fourier transformation). Prior to application
    of the correction filter to the time series passed to the algorithm, the
    correction filter is transformed to the time domain, tapered, and then
    transformed to the Fourier domain again. The values of the taper are:
      0                              if       t <  t1
      0.5-0.5*cos(pi*(t-t1)/(t2-t1)) if t1 <= t <= t2
      1                              if t2 <  t <  t3
      0.5+0.5*cos(pi*(t-t3)/(t3-t4)) if t3 <= t <= t4
      0                              if       t >  t4

Test-cases are set up for [soutifu](https://git.scc.kit.edu/Seitosh/Seitosh/blob/master/src/ts/wf/soutifu.cc) and are described in the accompanying [README.soutifu](https://git.scc.kit.edu/Seitosh/Seitosh/blob/master/src/ts/wf/testcases/README.soutifu).

A vendor update has taken place in [thof/IFOS2D](https://git.scc.kit.edu/thof/IFOS2D) see [issue 5](https://git.scc.kit.edu/thof/IFOS2D/issues/5) there. The code in contrib compiles and installs well. The integration into IFOS2D still is to be tested.

See merge request !3

Write measured and synthetic seismograms after the application of time windowing and frequency filtering  to disk if TIME_FILT and WRITE_FILTERED_DATA is set to 1. The string „su.filtered“ will be added to the filename.

Merge branch 'vendor_Seitosh' into import_Seitosh

Conflicts:
	contrib/fourier/Ffcommand.f
	contrib/fourier/Ffilters.f
	contrib/fourier/Fpolesnzeroes.f

Commands executed are:

    git merge -X theirs vendor_Seitosh
    git rm contrib/fourier/*.f

Fortran files are removed intentionally, since they are not used in IFOS2D.
This way IFOS2D does not need a Fortran compiler to be installed.

Drop current version of Seitosh code. The contents are taken vom branch master
of [Seitosh](https://git.scc.kit.edu/Seitosh/Seitosh). The current master
commit in Seitosh is 890d2fe565.

With this vendor drop the new taper feature as implemented in libstfinv
becomes available. Source time function correction filters produced in the
Fourier domain can be tapered in the time domain prior to application.

Commands executed in the root directory of IFOS2D:

    rm -rfv contrib
    mkdir -pv contrib
    (cd ~/git/Seitosh/src/libs/libaff; tar cvf - $(git ls-files)) \
      | ( cd ~/git/IFOS2D/contrib; mkdir aff; cd aff; tar xvfps -)
    (cd ~/git/Seitosh/src/libs/libfourier; tar cvf - $(git ls-files)) \
      | ( cd ~/git/IFOS2D/contrib; mkdir fourier; cd fourier; tar xvfps -)
    (cd ~/git/Seitosh/src/libs/libseife; tar cvf - $(git ls-files)) \
      | ( cd ~/git/IFOS2D/contrib; mkdir libcseife; cd libcseife; tar xvfps -)
    (cd ~/git/Seitosh/src/libs/libstfinv; tar cvf - $(git ls-files)) \
      | ( cd ~/git/IFOS2D/contrib; mkdir stfinv; cd stfinv; tar xvfps -)
    git add --force contrib

Since Seitosh on purpose does not provide export branches where source code
exports would be assembled in a hand-picked fashion, whole subdirectories from
Seitosh are simply copied. As a conseqeunce, the directory libcseife now also
contains Fortran code not really required by IFOS2D.