Log Message:
sysutils/xplr: update to 0.17.3

Changes & fixes:
-Added new fields border_type and border_style for all the panels to enable
 customizing the borders (see #450).
-Added boolean option xplr.config.general.enforce_bounded_index_navigation to
 configure wrapping on move (see #441).
-The built-in init.lua has been fully documented (see #445).
-Categorized the full list of messages using auto generation of docs from
 code (see #444).
-Some code refactor and documentation improvements.