Verse ref integrity validation

[ryderwishart]

• [ ] Test that vref checking is operating as expected

Refs #45 #39 #25

[birchamp]

• Making sure that the verse references are in the right order
• Making sure all the verses exist

Are there any other verse ref validations that need to be tested?

[BenjaminScholtens]

@birchamp it should also give warning for duplicates

[elsylambert]

Verified Verse Reference looks good and when there is a missing or duplicate verse, spell check shows the correct options to Quick fix.