Improve the keymapper

The keymapper, available as one of the options in the starting menu when the EXE is run without a scenery specified, has undergone a few changes:
- Key descriptions are now parsed the way Starter does and are displayed in the window. They are also no longer consumed when saving to a file.
- Unbound keys are now also displayed as well. Not all of them though; some entries won't exist if they are not specified in the eu07_input-keyboard.ini file.
- You can now unbind a key by pressing F10.

The Parser has got a new boolean option: `skipComments`, true by default to leave current behavior unchanged. When set to false, comments will be parsed as ordinary tokens.

parser.cpp

@@ -202,7 +202,7 @@ std::string cParser::readToken( bool ToLower, const char *Break ) {
                 token += c;
                 if( findQuotes( token ) ) // do glue together words enclosed in quotes
                     continue;
-                if( trimComments( token ) ) // don't glue together words separated with comment
+                if( skipComments && trimComments( token ) ) // don't glue together words separated with comment
                     break;
             }
             if( c == '\n' ) {