initial patch version
recode as suggested by @staabm  in https://github.com/redaxo/redaxo/pull/155#discussion_r1913479
make param string case independent as suggested by @gharlan in https://github.com/redaxo/redaxo/pull/155#discussion_r1913602
case independent URL param as suggested by @Koala in https://github.com/redaxo/redaxo/pull/155#discussion_r2342434
Merge pull request #76 from jdlx/core/rex_list/initial_sort_direction_patch

[rex_list] Spaltensortierung beliebig einstellbar (reopened)