[Therion] new Therion 5.5.4

[Therion]

Hi, there is a new release 5.5.4 of Therion.
Release notes:

v5.5.4          Therion 5.5.4 (2020-12-15):
    
    therion:
     * added layout-statistics carto|copyright-count
     * use unique pointers in thdatabase [#296]
     * added support for 270 to 360 degrees gradient readings
     * bugs fixed
       - scrap -walls off not working [#297]
       - various fixes [#293,294,295,296,298,299,301,302,303,305]
    
    thbook:
     * support smaller page formats (configuration at the line 5 of the file
       thbook/thbook.tex)
    
    loch:
      * bugs fixed:
        - fix display of Survex 3D with LRUD [#286]
        - read splay flag from Survex 3D files [#287]
    
    make:
     * allow -j$N [#283]
     * allow passing of WX_CONFIG variable [#284]
     * remove local copies of getline and getopt [#290,306]
     * small fixes
    
    infrastructure
     * use Github actions instead of Travis CI

Best regards,
Therion team