renamed event_analysis_widget to event_analysis_plot_widget
use PEP8 naming conventions
close an open reader at end of test
added some tests for HistogramItem
renamed kargs to kwargs
added more tests of HistogramItem
make sure to copy the self.bins, as it gets returned from a function and is changed
Merge pull request #5 from parkin/issue2

Copy HistogramItem bins array so it doesn't get modified accidentally. Added tests for HistogramItem.