Fix CMD help and select latest version by default

Author: jyapayne

command_line.py

@@ -576,7 +576,7 @@ def load_from_json(self, json_str):
 
     def selected_version(self):
         """Get the currently selected version from the NW.js dropdown"""
-        return self.get_setting('nw_version').value
+        return self.get_setting('nw_version').value or self.get_setting('nw_version').values[0]
 
     def extract_files(self):
         """Extract nw.js files to the specific version path"""

files/settings.cfg

@@ -248,7 +248,7 @@ linux_64_dir_prefix = 'nwjs-v{}-linux-x64'
     [[download_settings]]
         [[[nw_version]]]
             display_name='NW.js version'
-            required=True
+            required=False
             default_value=None
             values=[]
             type='list'