added change log

* version 1.0.8 (Apr 7, 2020)

- [MM] test version of direct bgr subtraction

- [MM] test version of multiple ref/bgr matches

- [PZ] allow to overwrite certain parameters on read

    * for now we can specify sample_temp and scattering_angle

    * in addition to (previously defined) phase_offset and tfac

    * example: read s1234.echo as sample sample_temp 273.15 scattering_angle 2.3

- [PZ] reduction parameter r.fqt_maxsigma now means absolute (not relative!) $\sigma_{F(Q,t)}$

    * default value is 1.0

- [PZ/MM] number of bug fixes

    * bug fix int read_data for JNSE array bounds

    * before clearing matches, check if valid scan (caused crash on some macOS machines)

    * warning if empty collection e.g. when q limits outside data range (instead of silent ignore)

    * goto label in macros can now be longer than 8 characters

    * fix runtime error when -s/-e options expect an int (see drspine -h)

    * commented out "test" messages and unused variables

    * make program params more consistent

    * appendix describing drspine parameters (design.pdf, appendix G)

    * clarifications in describing coordinate system (design.pdf, appendix C)

* version 1.0.1 (Oct 24, 2019)

- previous "official" release