added deterministic but unredictable hash generation for dir hashes, which should be preserved accross reboots. Should fix the msg from friends sending requests for the "wrong" dir hashes.

libretroshare/src/file_sharing/directory_updater.h

@@ -41,6 +41,9 @@ public:
     void forceUpdate();
     bool inDirectoryCheck() const ;
 
+    void setHashSalt(const RsFileHash& hash) { mHashSalt = hash; }
+    const RsFileHash& hashSalt() const { return mHashSalt; }
+
     void setFileWatchPeriod(int seconds) ;
     uint32_t fileWatchPeriod() const ;
 
@@ -60,6 +63,8 @@ private:
     HashStorage *mHashCache ;
     LocalDirectoryStorage *mSharedDirectories ;
 
+    RsFileHash mHashSalt ;
+
     time_t mLastSweepTime;
     time_t mLastTSUpdateTime;