Refactor analysis.py in to separate classes and files

No code changes other than adding a class hierarchy.

This is the first of a set of restructurings to support
adding additional tools that require log parsing.

Change-Id: Ifafd02cb3e755e146e21d146e12482ec799de702
diff --git a/frc971/analysis/plot_action.py b/frc971/analysis/plot_action.py
index 2f50ffd..d7dd48d 100755
--- a/frc971/analysis/plot_action.py
+++ b/frc971/analysis/plot_action.py
@@ -2,7 +2,7 @@
 
 import sys
 import numpy
-import analysis
+from plotter import Plotter
 import argparse
 
 def ReadPlotDefinitions(filename):
@@ -62,7 +62,7 @@
 
   args = arg_parser.parse_args(sys.argv[1:])
 
-  p = analysis.Plotter()
+  p = Plotter()
 
   # If the user defines the list of data to plot in a file, read it from there.
   if args.plot_defs: