Current devel version will be numbered 5.3.0 and it is planned to be released in the autum 2019.
Previous devel, current stable, version was 5.3.x (released on October, 2019), see what was new in that release at:
This is a draft of new features added in devel version, manually updated, thus not always synchronized with what is new in source code repository.
Flexible headers management via $xavp and $x_hdr exported variables.
Added new cfgt.list and cfgt.clean RPC commands
Added path value to xavp_rcd location record
Added xavp_rcd_mask parameter to control what values to skip