Improve LASSIE shortcuts, XML readability, and Modifier layout

[DiyunZ]

Summary

Improves editing consistency and readability in LASSIE.

1. Consistent shortcuts and object copy/paste

• Adds copy/paste support to the Objects List, child-event lists, Envelope Library, and Markov Model Library.
• Keeps object copies within their originating open project.
• Preserves pending edits when copying and avoids marking unchanged objects as modified.
• Checks child-event references before pasting to prevent restoring references to deleted or renamed objects.
• Standardizes closing secondary windows and dialogs while preserving their existing cancellation and confirmation behavior.
• Keeps text-field shortcuts separate from object-list shortcuts, so copying text does not unexpectedly copy an object.

2. More readable Result String XML

• Displays XML with indentation, a monospaced font, and a larger reading area.
• Keeps the XML editable and preserves manual content when opening the Function Generator.
• Converts valid XML back to compact form when used, while preserving parameter content.
• Leaves malformed XML visible for troubleshooting instead of silently replacing it.

3. Responsive Modifier layout

• Prevents “Default ON:” from overlapping the modifier-type selector in smaller windows.
• Keeps the label and percentage control together.
• Allows controls to wrap and the row to grow vertically when space is limited.
• Returns to a single row when enough space is available, without changing modifier parameters.

Keyboard shortcuts

The main shortcuts covered by this update are:

Action	macOS	Windows / Linux
Copy selected objects	Cmd+C	Ctrl+C
Paste copied objects	Cmd+V	Ctrl+V
Close a secondary window or dialog	Cmd+W	Ctrl+W

Object copy/paste requires focus on the corresponding list. Windows also supports Ctrl+F4 for closing secondary windows. These closing shortcuts do not replace the main application's quit behavior.

Existing project shortcuts remain unchanged:

Action	macOS	Windows / Linux
New project	Cmd+N	Ctrl+N
Open project	Cmd+O	Ctrl+O
Save	Cmd+S	Ctrl+S
Save As	Cmd+Shift+S	Ctrl+Shift+S

Close issue #41 and issue #3