Support for comments starting with '?'

data/test.mod

 : sample file
+? another style of comments
 
 NEURON  {
     THREADSAFE
@@ -26,7 +27,7 @@ PARAMETER {
     gkbar   = 0.1  (mho/cm2)
     celsius
     ek      = -100 (mV)    : must be explicitly def. in hoc
-    v       (mV)
+    v       (mV)           ? another style of comment
     vhalfm  =-43   (mV)
     km      =8
     vhalfh  =-67   (mV)

modcc/lexer.cpp

@@ -78,8 +78,9 @@ Token Lexer::parse() {
                 location_.line++;
                 continue;   // skip to next line
 
-            // comment (everything after : on a line is a comment)
+            // comment (everything after : or ? on a line is a comment)
             case ':' :
+            case '?' :
                 // strip characters until either end of file or end of line
                 while( !is_eof(*current_) && *current_ != '\n') {
                     ++current_;