Will write filtered and windowed displacement seismograms to disk.

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.

(1.)
Renamed function err() to declare_error().
This was a problem, as many standard libraries also has functions err().

(2)
I fixed a lot of compiler warnings like unused variables and uninitialised variables. However, here is a lot of work to do.

INVMAT - > FORWARD_ONLY
INVMAT1 - > PARAMETERIZATION

Renaming of observed seismograms:
SEIS_FILE_z.su -> SEIS_FILE_vz.su
SEIS_FILE_x.su -> SEIS_FILE_vx.su
SEIS_FILE_y.su -> SEIS_FILE_vy.su

Either rename your observed data, or (if synthetic) rerun forward modeling, so IFOS will create observed data, which is correctly named.

! This commit renames DENISE to IFOS !
Keep care and update all of your self written shell scripts etc.
The make target is 'IFOS' (capital letters).
The resulting binary is called 'IFOS' as well.

Added the option WRITE_FILTERED_DATA to write time filtered measured data to disk.
If WRITE_FILTERED_DATA is not set in the JSON file, it will be set to 0.

Update: Merge test