Don't draw any whitespaces by default

also fix the warning from Spirit

src/files.h

@@ -38,7 +38,7 @@ const std::string configjson =
 "        \"cleanup_whitespace_characters_comment\": \"Remove trailing whitespace characters on save, and add trailing newline if missing\",\n"
 "        \"cleanup_whitespace_characters\": false,\n"
 "        \"draw_spaces_comment\": \"Determines what kind of whitespaces should be drawn. Use comma-separated list of: space, tab, newline, nbsp, leading, text, trailing or all\",\n"
-"        \"draw_spaces\": \"space, tab, nbsp, trailing\",\n"
+"        \"draw_spaces\": \"\",\n"
 "        \"show_map\": true,\n"
 "        \"map_font_size\": \"1\",\n"
 "        \"spellcheck_language_comment\": \"Use \\\"\\\" to set language from your locale settings\",\n"

src/source.cc

@@ -4,7 +4,9 @@
 #include "terminal.h"
 
 #include <boost/property_tree/json_parser.hpp>
-#include <boost/spirit/include/qi.hpp>
+#include <boost/spirit/home/qi/char.hpp>
+#include <boost/spirit/home/qi/operator.hpp>
+#include <boost/spirit/home/qi/string.hpp>
 
 #include <gtksourceview/gtksource.h>