Arrange things so that "open parent" selects the file child when the parent is a directory

src/rcldb/rcldoc.cpp

@@ -20,6 +20,7 @@
 
 namespace Rcl {
     const string Doc::keyurl("url");
+    const string Doc::keychildurl("childurl");
     const string Doc::keyfn("filename");
     const string Doc::keyipt("ipath");
     const string Doc::keytp("mtype");

src/rcldb/rcldoc.h

@@ -194,6 +194,9 @@ class Doc {
     // enforced in internfile.cpp and misc other bits of metadata-gathering 
     // code
     static const string keyurl; // url
+    // childurl. This is set when working with the parent of the result, to hold
+    // the child of interest url, typically to highlight a directory entry
+    static const string keychildurl; 
     static const string keyfn;  // file name
     static const string keyipt; // ipath
     static const string keytp;  // mime type