Add tags column to sheetsync

New tags column shunts all columns after it right by 1.

Note we parse tags by splitting on commas then discarding whitespace.
If this would create an empty string tag, it is ignored.
Example: "foo, bar baz,a,,bc " -> ["foo", "bar baz", "a", "bc"]

sheetsync/sheetsync/main.py

@@ -91,6 +91,7 @@ class SheetSync(object):
 			'image_links': 6,
 			'marked_for_edit': 7,
 			'notes': 8,
+			'tags': 9,
 			'video_link': 11,
 			'state': 12,
 			'edit_link': 13,
@@ -106,6 +107,7 @@ class SheetSync(object):
 			'event_end': self.parse_bustime,
 			'poster_moment': lambda v: v == u'[\u2713]', # check mark
 			'image_links': lambda v: [link.strip() for link in v.split()] if v.strip() else [],
+			'tags': lambda v: [tag.strip() for tag in v.split(',') if tag.strip()],
 			'id': lambda v: uuid.UUID(v) if v.strip() else None,
 		}
 		# List of input columns
@@ -118,6 +120,7 @@ class SheetSync(object):
 			'poster_moment',
 			'image_links',
 			'notes',
+			'tags',
 		]
 		# List of output columns
 		self.output_columns = [