JSON Strings and GC Tokens

.. fix json writing so that user metadata no longer conflicts
   with the tokens used by GoldenCheetah, e.g. a user entered
   "NM" in the workout code and that conflicted with the
   token used to delimit a torque value.

.. all user strings are now saved with a space " " appended to
   the value and when read, if there is a trailing space it is
   removed.

src/JsonRideFile.y

@@ -78,6 +78,9 @@ static QString protect(const QString string)
     s.replace("\f", "\\f");  // formfeed
     s.replace("/", "\\/");   // solidus
 
+    // add a trailing space to avoid conflicting with GC special tokens
+    s += " "; 
+
     return s;
 }
 
@@ -91,6 +94,9 @@ static QString unprotect(const char * string)
     // in quotes. Lets strip those first
     QString s = string2.mid(1,string2.length()-2);
 
+    // does it end with a space (to avoid token conflict) ?
+    if (s.endsWith(" ")) s = s.mid(0, s.length()-1);
+
     // now un-escape the control characters
     s.replace("\\t", "\t");  // tab
     s.replace("\\n", "\n");  // newline