update to 5.0.4
    
    - switch Motif library to original Motif (as it's in Fedora since long)
    - link against new-style atlas library (atlas 3.10.1+)
    - BR: boost-devel
    - csh/zsh completion removed upstream
    - move bash completion into main package
    - separate ngmx and mdrun dropped upstream
    - enable testsuite
    - factorize a lot of build logic
    - drop redundant comments