ENH: Add Axis Settings Modal

[zdomke]

Add a modal for controlling the settings of an axis.

The modal class, AxisSettingsModal, takes in 3 arguments:

• parent: QWidget
  • This is the parent object of the modal. Should be whatever button opens the modal
• plot: PyDMArchiverTimePlot
  • This is the main plot of Trace
  • This is only used for redrawing the plot when the orientation changes. This should probably be done in PyDM instead of here
• axis: BasePlotAxisItem
  • The axis item that is controlled by the modal

The modal contains settings for:

• Changing the axis' orientation (left/right side)
• Enabling/disabling log mode for the axis
• Enabling/disabling gridlines on the axis
  • The opacity relies on the opacity slider from the PlotSettingsModal. This is done to keep the gridline opacity consistent across the plot

[ngAlexander9]

okay!

[zdomke]

Just realized that I didn't include a way of changing the axis' name. This should be included in this settings modal, similar to the name in #138.

[zdomke]

Just realized that I didn't include a way of changing the axis' name. This should be included in this settings modal, similar to the name in #138.

Holding off on this change for now. I talked with @shilorigins and we might make the axis labels in #139 editable instead.

[YektaY]

This looks good to me--you may want to add docstrings to some of the new methods. but that can also be done in a later pass