Fix N42 files having a bunch of extra null bytes at end of file, not parsing.

Author: wcjohns

src/SpecFile_n42.cpp

@@ -8856,6 +8856,12 @@ namespace SpecUtils
       reset(); 
 
       data_end = convert_n42_utf16_xml_to_utf8( data, data_end );
+
+      // Some times a bunch of null characters can get appended to the end
+      //  of the file - lets remove them, or rapidxml::parse will fail.
+      //  TODO: bet yet, we should look for the last '>' character, or even better, the last valid closing tag
+      while( ((data_end - data) > 2) && ((*(data_end - 1)) == '\0') )
+        --data_end;
 
       if( !is_candidate_n42_file(data,data_end) )
         return false;