Read in all gauge data at once when gauge is requested

Instead of opening up the fort.gauge data file and reading only one gauge this
patch reads all of the gauges in at once and stores them for later access.
This removes the ability of a `GaugeSolution` to read in itself directly.
Turn Warnings into print statements
Move gauge data pointer to AMRClaw repos
Add reference to amrclaw GaugeData class
Add simple convenience script

Adds a simple script that can be then put on the path for easy interactive plotting.
Merge pull request #30 from mandli/read-all-gauges

Read in all gauge data at once when gauge is requested
Add ImportError catch for GaugeData import

Since the class GaugeData was moved to the AMRClaw repository, this adds an
import try/except clause that catches on an ImportError which then prints
a warning message and returns from the calling function.
Fix incorrect module import bug
Remove pdb calls
Previous bug fix not applied...
Merge remote-tracking branch 'clawpack/master'

Conflicts:
	src/python/visclaw/data.py