* Make it possible to disable a module for a renderer
* Put DesktopCapturer API under a build flag
The name is "enable_desktop_capturer".
Enabled by default.
This change gives sandboxed renderer scripts a similar structure to what already
exists in the lib/{browser,renderer,common} directories.
It also allows sandboxed renderer initialization to share more code with
non-sandboxed renderers (ipcRenderer is now imported directly from
lib/renderer/api/ipc-renderer).
