(matches the receiver used by rec_plane

Segy isn't used in our working group and therfore not tested.
Also an segy Input for the obeserved seismograms is missing.
In future options for reading binary and ascii seismograms should be implemented

Updated the seismograms in documentation
with seismograms from the updated script
and cleanup of old figures

- slice2D_toy_model.m now reads source and receiver positions and plots them if the positions are located in the current 2D slice
- One figure in the manual had old coordinate system (fixed)
- removed old figures in git

- old file name: seismo1_toy -> changed to seismo_trace_toy

- input data of folder /par/su and /par/su_obs resp.
- using function su2matlab instead of binread to read binary files
- added layout (legend, text boxes for the components)
- divided variable t by 10^6 to get time in seconds

exportfig is an extarnal matlab script

And a few adaptions to existing scripts

Still changes to be done in toy example chapter.
(figures with rotated coordinate system)

Conflicts:
	src/ifos3d.c
	src/steplength.c

Switched coord. system for the model input and output to be similar to
Sofi3D. Unlike in the code where z is the fast dimension, the in/output
uses y (depth) as fast and z as slow dimension.
That means by using for example ximage(2D) to visualisze the model you will see NZ x-y planes.

(z<->y): y is now vertical for input/output like in the whole code.
Note that the output and input of the models stayed the same.
The order of the loops over the model should be the same in every function. (The most efficent order)
The models have as fast (n1) directon the z (horizontal) component.
n1/n2/n3 = z/x/y. So with ximage you will see horizontal (n1(z),n2(x)) slices forom top to bottom.

script runs forward and inversion

defined optinal parameters
READREC is now the switch for 0-receiver line / 1-from file / 2-receiver array
using only one receiver specified in the input file is now possible.
if rec array is used checkfd_ssg was checking the wrong input parameters from the .inp files
etc.

+ few addidtional changes:
SRCREC is now the switch to either read from .dat file =1 or use plane wave =2
reduced some arrays (currently unused) to variables

test steplength set to 0.5 aand 1.0