Minor GUI bug fix and QOL improvements

[lambjames18]

Only minor changes that improve QOL and remove a few small bugs

• Fixing a bug where an error message appears in the terminal after using the Configurator (no change to functionality).
• Adding a popup window that shows the current stage position (working distances and the stage position). Found myself wanting something like this when trying to update the working distance during an experiment.
• Modified how parameters are pulled from the scope (import imaging conditions, import laser parameters, import stage position). Previously, a valid general step was unnecessarily required. Now, it pulls in the connection_host and connection_port from the general step if those are present; otherwise, it assumes default values of "localhost" and an empty port, which should be correct on most standard installations.
• Adding in some constants/enums/namedtuples (types.py and constants.py) for EDAX functionality that will come in a future pull request.
• Changed default theme to be dark.
• Small edits to the parameters database (lookup.py). It now pulls available versions explicitly from types.py. Previously, it pulled the maximum version and assumed there were incremental steps between the minimum and maximum.
• Updated tooltip description of "laser beam shift" parameters based on McLean's comments in Laser Beam Shift / Laser Beam Centering #10.
• Minor edits that remove old and commented-out code.