show curve values and depth on hover

[JustinGOSSES]

No description provided.

[JustinGOSSES]

Eshan volunteered to possible do a pull request for this issue as he has some code he can share for it. Putting comment here as I don't know his github name.

[JustinGOSSES]

There are a couple versions of hover/tooltips.

This one looks nice and is independent of making circles over lines. https://bl.ocks.org/micahstubbs/e4f5c830c264d26621b80b754219ae1b

[JustinGOSSES]

Should solve this one and #59 at same time

[JustinGOSSES]

Changing how hover/mouseover appears requires the following switches to be available to user:

1. • Any hover display of information?
2. • Depth or depth & curve displayed
3. • if curve in any above, which curve
4. • if curve, what color if not default of curve color & infill of black to ensure visibility

How to ensure intuitive for developer?
A.) Give available values in key name
B.) Have these key:value pairs at curvebox level
C.) Only supply mouseover value for one curve at a time as otherwise things overlap and can't be seen. If you want to give user ability to switch between curve values on hover, rebuild the svg.
mouseover_yes_or_no = "yes" or "no" string
mouseover_depth_or_depth_and_curve = "depth" or "depth_and_curve" string
mouseover_curvename = "GR" or other curvename string, default is first curve
mouseover_color_or_default_which_is_curve_color = "default" or a color as a string