v0.4.1: fix many bugs; find/replace form improvements; better chunking

[0.4.1] - 2023-03-08

Fixed

1. Entering an invalid regex (e.g., unbalanced parentheses) in the find/replace form no longer causes plugin crash and instead simply causes a message box to pop up and an early return. However, the find/replace form's tree view is lost as a result, and so the find/replace form will need to be closed and reopened afterwards.
2. Next chunk and First chunk plugin commands (and associated buttons on chunk form) now add a new chunk if you were already on the last chunk (for Next chunk) or no chunks had been added.
3. Reduced flickering when moving between find results in the find/replace form.
4. Fixed bug where chunking a JSON file and then chunking another JSON file would cause the second file to be chunked incorrectly.

Added

1. First chunk, Last chunk, and Next chunk plugin commands all scroll the selected tree node into view on the chunk form.
2. Show total match count on find/replace form, and indicate if fewer matches are shown than the total number found. Do the same for each chunk.