title: vscode: is there an api for accessing config values from a vscode extension
body: <p>I am writing an extension for vscode 1.12.2 and I am trying to determine the default theme.  Atom Editor has a nice <a href="https://atom.io/docs/api/v1.17.0/Config" rel="noreferrer">API for accessing config values</a>, e.g.:</p>
  
  <pre><code>atom.config.defaultSettings.core.themes[0]
  "one-dark-ui"
  atom.config.defaultSettings.core.themes[1]
  "one-dark-syntax"
  </code></pre>
  
  <p>Is there something similar to this in vscode?  </p>
  
  <p>I can see the value 'workbench.colorTheme' in <code>~/AppData/Roaming/Code/User/settings.json</code>:</p>
  
  <pre><code>   // "terminal.integrated.shell.windows": "/Program Files/Git/bin/bash.exe"
      "terminal.integrated.shell.windows": "C:\\Windows\\System32\\cmd.exe",
      "terminal.integrated.shellArgs.windows": [
          "/k",
          "C:\\Program Files\\Git\\bin\\bash.exe"
      ],
      "workbench.colorTheme": "Default Light+" &lt;-- here
  </code></pre>
  
  <p>However, I'd rather not resort to a custom solution whereby I directly read the config file as JSON, especially since it allows non-default JSON values such as comments, which I would presumably have to pre-parse-out.</p>
  
  <p>While this question is narrowly directed at determining the theme, it really applies to any config parm.  I didn't see anything in the <a href="https://code.visualstudio.com/docs/extensionAPI/vscode-api#_env" rel="noreferrer">vscode html api</a> or in browsing the typings file <code>/c/Program Files (x86)/Microsoft VS Code/resources/app/out/vs/vscode.d.ts</code></p>