log an error to console if the first element of the array passed to histogram is not a number.
add http prefix to source tags in index.html so it runs locally
change http -> https
Merge pull request #125 from tlatorre-uchicago/histogram-typeerror

Histogram TypeError
Properly set min_y for log scales when there are negative values. Set min_y=0.1 for histograms with a log scale so that bins with a single count are visible.
fix log histogram logic
fix log10 logic
added first barplot prototype for #126
added barplot prototype to wrong section
first pass at smoothers. Added ls, still need to debug lowess.
make the bounding boxes halfway between the previous point and the next point. fixes issue #98.
fixed the messy lowess and ls functions
slightly more styling work on bar charts, and also removing .attr('class',...) in favor of .classed(...)
compute args.scalefns.xf() once for rollover rectangles.
fix indent
a bunch of cosmetic changes. Lightened ever-so-slightly the extended ticks. Also provided a new x_axis and y_axis arguments, which defaults to true, but if set to false it does not draw the axis (but it does obviously make all the scales). This was originally implemented to make the bar charts look slightly better, but might as well keep for all graphics.
another small cosmetic change to bar charts
Merge pull request #128 from tlatorre-uchicago/large-gaps

Fixes issue #98
Fix issue #129
Fix issue #130