pytimetag: make color map configurable
pytagtime: new plot types, normalized hour-of-day, day-of-week plot
pytagtime: plot labels and limits
pytagtime: remove NaN values from pie chart
pytagtime: skip specified days of the week (e.g. concentrate on weekends)
Merge pull request #25 from temporaer/master

PyTagTime: new plot type, colors, better normalization of plots, better NaN handling