Suggestion: default for line shape be changed.

[GregorySchwartz]

Although subjective, I believe the default line shapes should be:

lineStyle . _lineCap .= LineCapSquare
lineStyle . _lineJoin .= LineJoinBevel

Particularly LineJoinBevel. The default is very misleading. For instance, using the code in https://github.com/cchalmers/plots/issues/34 without that line result in a large angular join which extends beyond the axis to such a large degree, even though the values never go below 0.

[cchalmers]

I thinkLineJoinBevel for line plots looks a little strange. I had a little look around and the defaults for the line joins are:

• pgfplots: miter
• gnuplot: miter
• ggplot: round
• matplotlib: round

Everyone uses butt for the default line cap. I could be persuaded to change the default to LineJoinRound but personally I think miter goes better with rest of the default look.

I'll admit the case in #34 is particularly bad but it's easy enough to change the join. Also the default is to crop plots to the axis bounds so if yMin was set to 0 the join wouldn't have extended below 0.

[GregorySchwartz]

Ah, I am used to ggplot and matplotlib so my preference was biased more towards those less angular looks.