"Delete" button to delete existing textblocks

[GeorgeCiesinski]

Description:

Add a button to delete existing textblocks

Solution:

1. A delete button is placed on the root window under the textblocks display. Clicking this checks to ensure a textblock has been highlighted in the textblock window. If yes, it opens a toplevel widget with:

• A message advising the user that the textblock is about to be deleted.
• If the textblock is located in the remote directory, an additional message will indicate that this is a shared textblock.
• Finally, a message asking the user if they are certain they want to delete it.
• A "yes" button
• A "no" button

2. Clicking yes deletes the textblock and closes the window. Clicking no closes the window.
3. Automatically reload textscript.

[GeorgeCiesinski]

Added toplevel widget in commit 5fe1d97