potential memory improvement

I've been loading a BIG group off newsfeeds.com and my ISP, and Pan
(0.126) often gets up to 2G of memory usage when I visit this group.
I'm starting to look into the usage of STL within the Quark class.

I'm probably not going to find big areas for improvement on memory
usage, but I'm going to try.

I think that __gnu_cxx::hashtable can be used instead of 
__gnu_cxx::hash_map for Quark._lookup.  That could save the size of a 
StringView for each entry in the hashtable.  hash_map is redundant 
because in each node, it stores a key-value pair; the value that Quark 
is storing (Impl) already contains the key.  I'm looking in to this.  If 
anyone else wants to look into it, it'd be nice.  I haven't touched C++ 
in several years.


Ken