bluetooth.js: init func & implement isXXX funcs
bluetooth.js: init func & implement isXXX funcs

Added:
  - init():  needed for proper btmod setup
  - bt_XXX:  private vars, bt mod specific
  - DevInfo: struct containing basic info about bt device

Implemented:
  - init()
  - isConnected()
  - isVisible()
  - isSearching()
  - list()

funmaker/B-chat,funmaker/B-chat