FIX: Import & Export for UI Redesign

[zdomke]

Description

Fix importing and exporting of config files for Trace. These features are now available under the Trace action menu in the top left of the app as Save, Save As..., and Open Trace Config....

• Open Trace Config... action: Prompt the user for a file to open in Trace
  • Allows users to load config files for Trace (.trc), Striptool (.stp), or Java Archive tool (*.xml)
  • Will create the state saved in the config file (axes, curves, plot settings, etc.)
• Save As... action: Prompt the user for a file to save the config to
  • Overwrites existing files if requested by the user
  • Only allows users to save as Trace config files (*.trc)
• Save action: Saves any changes to the file that was opened last
  • The file affected by this is not marked anywhere. Requested in [FEATURE] - Imported File Name #85
  • If no file was opened, this works the same as the Save As... action

Changes to ControlPanel class

Methods for adding curves and axes now return the CurveItem or AxisItem that is instantiated.
Added new methods for:

• Removing all axes and curves from the ControlPanel
• Getting an existing AxisItem
• Setting all axes and curves in the ControlPanel

Changes to PlotSettingsModal class

Add new checkbox to enable/disable all Y-Axis gridlines.
Also added a new method for altering the settings of the plot based on a given config dictionary. Both of these changes are necessary for the import/export capabilities.

[zdomke]

Found a bug a little bit ago where curves do not successfully get removed from the plot before an import. This results in "dead" curves staying on the plot without a way of being removed.

Looking into this now.

[YektaY]

Read through the changes, and everything looks good to me. Great work!