name-value-convert & name-value-get: ptree.h fix for  outputing a ptree that is loaded with json data. The bug exists for json arrays 1) it now keeps the correct path value for array items 1) options --show-path-indices [--no-brackets] added to show array indices with path elements e.g. flight_levels[0]/levels[1]="20000"
Merge branch 'master' of https://github.com/acfr/comma