Expose a way to embed "raw" data values within Buefy grid data

for sake of custom front-end stuff

tailbone/grids/core.py

@@ -1124,8 +1124,17 @@ class Grid(object):
             rowobj = raw_data[i]
             row = {}
 
+            # sometimes we need to include some "raw" data columns in our
+            # result set, even though the column is not displayed as part of
+            # the grid.  this can be used for front-end editing of row data for
+            # instance, when the "display" version is different than raw data.
+            # here is the hack we use for that.
+            columns = list(self.columns)
+            if hasattr(self, 'buefy_data_columns'):
+                columns.extend(self.buefy_data_columns)
+
             # iterate over data fields
-            for name in self.columns:
+            for name in columns:
 
                 # leverage configured rendering logic where applicable;
                 # otherwise use "raw" data value as string