Previously we'd always stop org.domokit.sky.shell. If an
AndroidManifest.xml exists, we'll use the activity specified in there
instead.

flutter start no longer depends on a pre-built SkyShell.apk. It builds a
new one, as long as an AndroidManifest.xml exists.

We rebuild the .apk every time either AndroidManifest.xml or
flutter.yaml changes.

fixed sub-process stdout parsing; added todos

Add a --full-restart flag to the start command that controls whether we stop the application process

SkyActivity now allows reloading application Dart code within an existing
activity.  If a SkyActivity instance is already running, then passing
--no-full-restart will restart the Dart code without killing and restarting
the SkyShell application.
(full-restart will remain the default until the engine
that supports this is rolled out)

Also remove the obsolete --poke flag

rename to printTrace(), printStatus(), and printError()

remove device type specific checks

Was failing when starting in the iOS Simulator

@chinmaygarde

fix an issue where errors were printed twice

Fixes #1034, at least for start and listen.

iOS takes a different codepath and will need more work.

@chinmaygarde

1) Moved basic utility code into base/ directory to make it clear which code
   doesn't depend on Flutter-specific knowldge.
2) Move the CommandRunner subclasses into a runner/ directory because these
   aren't commands themselves.

Now you can supply a route argument to flutter start:

  $ flutter start --route /foo

which will start the app at /foo instead of /.

Example:
   cd flutter/examples/stocks
   flutter --engine-src-path /path/to/engine/src apk -o Stocks.apk -m apk/AndroidManifest.xml

Other changes in this patch:
- Make the 'flutter' tool say "Updating flutter tool..." when it calls
  pub get, to avoid confusion about what the pub get output is about.
- Make the bash flutter tool call pub get when the revision has
  changed. (This was already happening on Windows.)
- Fix a raft of bugs found by the analyzer.
- Fix some style nits in various bits of code that happened to be near
  things the analyzer noticed.
- Remove the logic in "flutter test" that would run "pub get", since
  upon further reflexion it was determined it didn't work anyway.
  We'll probably have to add better diagnostics here and say to run the
  updater script.
- Remove the native velocity tracker script, since it was testing code
  that has since been removed.

Notes on ignored warnings:
- We ignore warnings in any packages that are not in the Flutter repo or
  in the author's current directory.
- We ignore various irrelevant Strong Mode warnings. We still enable
  strong mode because even though it's not really relevant to our needs,
  it does (more or less accidentally) catch a few things that are
  helpful to us.
- We allow CONSTANTS_LIKE_THIS, since we get some of those from other
  platforms that we are copying for sanity and consistency.
- We allow one-member abstract classes since we have a number of them
  where it's perfectly reasonable.
- We unfortunately still ignore warnings in mojom.dart autogenerated
  files. We should really fix those but that's a separate patch.
- We verify the actual source file when we see the 'Name non-constant
  identifiers using lowerCamelCase.' lint, to allow one-letter variables
  that use capital letters (e.g. for physics expressions) and to allow
  multiple-underscore variable names.
- We ignore all errors on lines that contain the following magic
  incantation and a "#" character:
    // analyzer doesn't like constructor tear-offs
- For all remaining errors, if the line contains a comment of the form
    // analyzer says "..."
  ...then we ignore any errors that have that "..." string in them.

Now we suggest using -t to specify the main Dart file.

Fixes #53

We still have the --http option as a fallback for now. Once we're confident the
--no-http version works, we'll drop the --http support.

Also, create the FLX in a temp directory and then delete the temp directory
when we're done. Finally, pull the Linux artifacts from the cloud storage
bucket that the buildbot is uploading to.

This flag builds a local FLX file and pushes that to the device instead of
using an HTTP server.

remove an unused import

review comments

rename st --> stack

This patch makes `flutter start` work without a clone of the engine git
repository. Making this work pulled a relatively large refactor of how the
commands interact with application packages and devices. Now commands that want
to interact with application packages or devices inherit from a common base
class that holds stores of those objects as members.

In production, the commands download and connect to devices based on the build
configuration stored on the FlutterCommandRunner. In testing, these fields are
used to mock out the real application package and devices.

Also fixes some minor bugs with iOS and Android interactions.

I'm trying to get a feel for the code by writing some simple cleanup patches.

Also update tests to be compatible with the presence of iOS and add tests for list and install.