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/common.py

@@ -174,6 +174,26 @@ def hexToInt(value, default=0):
     return default
 
 
+def checkIntRange(value, first, last, default):
+    """Check that an int is in a given range. If it isn't, return the
+    default value.
+    """
+    if isinstance(value, int):
+        if value >= first and value <= last:
+            return value
+    return default
+
+
+def checkIntTuple(value, valid, default):
+    """Check that an int is an element of a tuple. If it isn't, return
+    the default value.
+    """
+    if isinstance(value, int):
+        if value in valid:
+            return value
+    return default
+
+
 # =============================================================================================== #
 #  Formatting Functions
 # =============================================================================================== #