Make it possible to plot all examples from memory.

(by adding "claw.setplot = setplot" and "claw.keep_copy = True")
Gracefully handle user errors in Controller.plot().
Allow more access to attributes of object members.

Let Controller access attributes of Solution, State, Grid.
Merge pull request #345 from ketch/plot_examples

Allow plotting of all examples from memory in PyClaw
Merge pull request #346 from ketch/access_member_attributes

Allow more access to attributes of object members.
Better interactive behavior of controller.

- Tear down solver when solver is deleted, not
  necessarily at end of controller.run()
- Use Python's __del__() method to tear down solver
- Don't overwrite old frames if controller.run() is called twice.

This allows for interactive things like:

(set controller up)
claw.tfinal = 1
claw.run()
(get some output frames)
claw.tfinal = 2
claw.run()
(more output frames get appended)
Set default parameters for some examples to yield more interesting results.
Merge pull request #348 from ketch/interactive_controller

Better interactive behavior of controller.
Merge pull request #349 from ketch/more_interesting_examples

Set default parameters for some examples to yield more interesting results
In shockbubble_scipy example, just import the one thing we need.
Merge pull request #353 from ketch/import_less

In shockbubble_scipy example, just import the one thing we need.
Make sure plotdata object always gets created.
Merge pull request #354 from ketch/better_controller_plotting

Make sure plotdata object always gets created.
Minor refactoring of I/O code (no change in functionality).
Fix I/O bug introduced in last commit.
Put options argument back in io/petsc.py read and write functions.
Status dictionary now refers to the whole simulation.

Also set +/- infinity values initially for cflmax, dtmax/min.
Merge pull request #358 from ketch/clean_up_io

Clean up I/O
Merge pull request #359 from ketch/fix_status

Status dictionary now refers to the whole simulation.
Write and read problem_data and mapc2p in both ascii and petsc formats.