Most of the getters in TunnelEntry are almost verbatim from
net.i2p.i2ptunnel.web.IndexBean and net.i2p.i2ptunnel.web.EditBean

There are a lot of changes here:
- The main_content FrameLayout is now main_fragment (more logical name).
- TunnelEntry now stores a Context instead of a TunnelEntryLoader (so
  it can be instantiated inside the detail Fragment).
- The activity_navdrawer layout is now an alias to a one-pane or two-pane
  layout depending on screen size.
- Subclasses of I2PActivityBase can now override canUseTwoPanes() to enable
  and use the two-pane layout (for devices that support it).

Until changes to the list of TunnelControllers can be monitored, the Loader
refreshes the view every 10 seconds.

Router must be started and client tunnels built before loading the I2PTunnel
Activity, or it hangs when switching tabs.

Previous commit was not broken, a clean build fixed the problem.

Broken: cannot find net.i2p.i2ptunnel.I2PTunnel
(but it can when launching the router)

Temporary; will eventually be in an about menu in settings

The navigation drawer has been (mostly) migrated to link to Activities instead
of Fragments. Only Activities can be searched via the inbuild Android search
function, which uses Intents.

This should have enabled the current navigation drawer entry to be highlighted
by the call to setItemChecked() in selectItem(), but it still doesn't work.