fixes skygragon#72: enhance editor feature.

Signed-off-by: Eric Wang <skygragon@gmail.com>

Author: skygragon

docs/advanced.md

@@ -54,6 +54,7 @@ Create a JSON file named `.lcconfig` in your home directory, e.g.
 
 	{
 		"LANG": "java",
+		"EDITOR": "vim",
 		"USE_COLOR": true,
 		"COLOR_THEME": "default",
 		"AUTO_LOGIN": false,
@@ -64,6 +65,7 @@ Here are some useful settings:
 
 * `AUTO_LOGIN` to enable auto login feature, see [Auto Login](#auto-login).
 * `COLOR_THEME` to set color theme used in output, see [Color Theme](#color-theme).
+* `EDITOR` to set editor used to open generated source file.
 * `ICON_THEME` to set icon them used in output.
 * `LANG` to set your default language used in coding.
 * `USE_COLOR` to enable colorful output.
@@ -133,4 +135,4 @@ You can easily introduce more features by installing other plugins form third pa
 
 * [leetcode-cli-plugins](https://github.com/skygragon/leetcode-cli-plugins)
 
-Feel free to try out the plugins above. Or you can develope your own plugins to enrich leetcode-cli's functionalities.
+Feel free to try out the plugins above. Or you can develope your own plugins to enrich leetcode-cli's functionalities.

docs/commands.md

@@ -94,6 +94,7 @@ Navigate the problems.
 	* database
 	* shell
 * `-s` to show statistic counters.
+* `-e` to open editor with generated source file.
 * `leetcode list <keyword>` to search by keyword matching.
 
 *Examples*

lib/commands/show.js

@@ -50,7 +50,6 @@ var cmd = {
     editor: {
       alias:    'e',
       type:     'string',
-      default:  '',
       describe: 'Pass generated source file to editor'
     }
   }
@@ -79,8 +78,8 @@ cmd.handler = function(argv) {
 
       core.exportProblem(problem, filename, !argv.extra);
 
-      if (argv.editor) {
-        childProcess.spawn(argv.editor, [filename], {
+      if (argv.editor !== undefined) {
+        childProcess.spawn(argv.editor || config.EDITOR, [filename], {
           // in case your editor of choice is vim or emacs
           stdio: 'inherit'
         });

lib/config.js

@@ -47,6 +47,7 @@ var DEFAULT_SYS_CONFIG = {
 var DEFAULT_USER_CONFIG = {
   AUTO_LOGIN:  false,
   COLOR_THEME: 'default',
+  EDITOR:      'vim',
   ICON_THEME:  '',
   LANG:        'cpp',
   MAX_WORKERS: 10,