67 add more operations

[rodolakis]

• close #67
• close #77

Plus a bunch of UI optimizations:

• tootltips
• adjust layout margins
• turn readOnly QLineEdit into QLabel (e.g. for displaying cursor position)

And, related to #90 & #73:

• made folder & file tabs closable
• add file path to the field table view panel

[rodolakis]

[rodolakis]

@MDecarabas if you get to this, in general you can ignore the changes made in the .ui (xml) files.

• the .ui files primarily relate to the graphical appearance of the application (define the layout and visual elements of the UI) and do not impact the core functionalities.
• the Python code handles the logic and functionalities. So unless there's a specific concern related to UI layout or aesthetics, you can focus your review on the Python code changes.