correct values input spec
improve module docstrings and code
improve module docstrings and code
improve module docstrings and code
improve module docstrings and code
improve module docstrings making it more pep8 compliant
improve module docstrings and code of histogram chart
improve module docstrings making it more pep8 compliant and improving code quality
improve module docstrings making it more pep8 compliant and improving code quality for TimeSeries, Step and Dot
move import on top of module
reorder methods definition to follow 'get_data', 'get_source', 'draw' order
Merge pull request #1552 from bokeh/task/charts_style_and_docstrings

Task/charts style and docstrings