Port get.py improvements from upstream.

Generally standardizes the get_* helpers:
 - Adds type hinting.
 - Deduplicates block property addition.
 - Respects `graceful` in more contexts.
 - More resilient to invalid user input / less boilerplate necessary
   at call-sites.

files/helpers/strings.py

@@ -1,8 +1,9 @@
-
 import typing
 
 # clean strings for searching
 def sql_ilike_clean(my_str):
+	if my_str is None:
+		return None
 	return my_str.replace(r'\\', '').replace('_', r'\_').replace('%', '').strip()
 
 # this will also just return a bool verbatim