reworked IOstreams

- Istream and Ostream now retain backslashes when reading/writing strings.
  The previous implementation simply discarded them, except when used to
  escape a double-quote or a newline. It is now vitally important to retain
  them, eg for quoting regular expression meta-characters.

  The backslash continues to be used as an escape character for double-quote
  and newline, but otherwise get passed through "as-is" without any other
  special meaning (ie, they are *NOT* C-style strings). This helps avoid
  'backslash hell'!
  For example,
     string:   "match real dots \.+, question mark \? or any char .*"
     C-style:  "match real dots \\.+, question mark \\? or any char .*"

- combined subfiles in db/IOstreams, some had more copyright info than code
- OPstreamI.H contained only private methods, moved into OPstream.C

Are these really correct?
   IOstreams/Istream.H:#   include "HashTable.C"
   token/token.H:#define NoHashTableC

applications/test/string/stringTest.C

@@ -48,11 +48,16 @@ int main(int argc, char *argv[])
     Info<< string(test).expand() << endl;
 
     string test2("~OpenFOAM/controlDict");
-    Info<< test2.expand() << endl;
+    Info<< test2 << " => " << test2.expand() << endl;
 
     string s;
     Sin.getLine(s);
-    Info<< s.expand() << endl;
+
+    string s2(s.expand());
+
+    cout<< "output string with " << s2.length() << " characters\n";
+    cout<< "ostream<<  >" << s2 << "<\n";
+    Info<< "Ostream<<  >" << s2 << "<\n";
 
     Info << "End\n" << endl;