Sharp lines for charts with step interpolation

[rightfold]

Step charts look quite fuzzy. It would be nice if there were an option for sharp lines, similar to the option that is available for grid lines.

[WofWca]

Workaround: consider lineWidth: 2

Possible solutions:

• Add/subtract 0.5 from x & y here:

  smoothie/smoothie.js

  Lines 970 to 971 in c849bef

  	context.lineTo(x,lastY);
  	context.lineTo(x,y);

  
  just as with grid's sharpLines . Though some might say that it makes the data displayed incorrect.
• Add an option called something like offsetPixels (or offsetPixelsX, offsetPixelsY) that would offset the whole canvas instead of just the data line. It's kind of conflicting with grid's sharpLines option though.