implemented most of rsdataservice,

updated rsnxsitems with discrete msgs and grp item rather than collection of msgs/grps
added flags header file 
added first declaration of implemented genexchange service (client API interface)

git-svn-id: http://svn.code.sf.net/p/retroshare/code/branches/v0.5-new_cache_system@5180 b45a01b8-16f6-495d-af2f-9b41ad6348cc

libretroshare/src/util/retrodb.h

@@ -149,6 +149,18 @@ public:
 
 private:
 
+    class RetroDbBlob{
+
+    public:
+
+        char* data;
+        uint32_t length;
+        uint32_t index;
+    };
+
+    bool execSQL_bind_blobs(const std::string &query, std::list<RetroDbBlob>& blobs);
+
+private:
 
     sqlite3* mDb;
 
@@ -260,6 +272,8 @@ public:
 
     /*!
      * Returns the value of the requested column as a String.
+     * data returned must be copied, as it is freed after RetroDb
+     * is closed or destroyed
      * @param columnIndex the zero-based index of the target column.
      * @return  the value of the column as pointer to raw data
      */