Ellipsize strings that are too long

[h1ckstead]

Text in some Labels can be too long and needs to be eclipsed and full text displayed in a tooltip:

• In the Session History block on Practice Page "correction_label" (now it is cut at 50 chars [:50])
• In the Vocabulary section on Vocabulary Page (now long words push the [Next] button and "Times to spell" label to the right)

Example without tooltip:
`import tkinter as tk

def truncate_text(text, max_length):
if len(text) > max_length:
truncated_text = text[:max_length-3] + "..."
else:
truncated_text = text
return truncated_text

root = tk.Tk()

root.columnconfigure(0, minsize=200)
root.columnconfigure(1, minsize=200)
root.rowconfigure(0, minsize=50)

label_text = "This is a long label that should be truncated if it exceeds the available space"
max_label_length = 25
truncated_label_text = truncate_text(label_text, max_label_length)

label = tk.Label(root, text=truncated_label_text, wraplength=180, anchor="w")
label.grid(row=0, column=0, sticky="w")

root.mainloop()`