Code and GUI text cleanup (#926)

* Move int range checkers from options class to common file
* Improve error handling and reporting
* Make some minor improvements to init and test suite
* Fix 'trypewriter' to 'typewriter' typo
* Remove menu path description in dialog help text
* Improve the help text for entries in the Format menu
* Reword a couple of dialog messages

novelwriter/dialogs/preferences.py

@@ -776,7 +776,7 @@ class GuiPreferencesEditor(QWidget):
         self.mainForm.addRow(
             self.tr("Scroll past end of the document"),
             self.scrollPastEnd,
-            self.tr("Also improves trypewriter scrolling for short documents.")
+            self.tr("Also improves typewriter scrolling for short documents.")
         )
 
         # Typewriter Scrolling