Changed the memory allocation strategy for NmapOutputTable from

estimating the worst-possible-case memory usage (the longest row
length times the number of rows) to a more reasonable dynamic
allocation of memory.  Now the buffer is started at 512 bytes and
approximately doubled each time it fills.  512 bytes is a compromise
that was determined empirically.  Most regular scans use less than 512
bytes.  Scans with -sV and especially -sC tend to use a few k of
memory.

See http://seclists.org/nmap-dev/2009/q1/0782.html for the tests.

NmapOutputTable.h

@@ -142,10 +142,6 @@ class NmapOutputTable {
   void addItemFormatted(unsigned int row, unsigned int column, bool fullrow, const char *fmt, ...)
 	  __attribute__ ((format (printf, 4, 5)));
 
-  // Returns the maximum size neccessary to create a printableTable() (the 
-  // actual size could be less);
-  int printableSize();
-
   // This function sticks the entire table into a character buffer.
   // Note that the buffer is likely to be reused if you call the
   // function again, and it will also be invalidated if you free the