put.c: track the fully qualified path of our position in the tree
put.c: track the fully qualified path of our position in the tree

Previously, we only tracked a path like /a/b/c and printed that in errors
to indicate where in the tree the error occurred. That was ambiguous when
there were multiple /a/b's for example. We now include the more precise
path /a[2]/b[3]/c in error messages to clarify that.

ptoscano/augeas,pevalme/augeas,mlichvar/augeas,hercules-team/augeas,lutter/augeas,manandbytes/augeas,ptoscano/augeas,mlichvar/augeas,pevalme/augeas,lutter/augeas,ptoscano/augeas,mlichvar/augeas,hercules-team/augeas,kunkku/augeas,manandbytes/augeas,pevalme/augeas,kunkku/augeas,lutter/augeas,kunkku/augeas