rename last fillmode to previous

public/app/plugins/datasource/mssql/partials/query.editor.html

@@ -55,7 +55,7 @@ Macros:
 - $__unixEpochFilter(column) -> column >= 1492750877 AND column <= 1492750877
 - $__timeGroup(column, '5m'[, fillvalue]) -> CAST(ROUND(DATEDIFF(second, '1970-01-01', column)/300.0, 0) as bigint)*300.
      by setting fillvalue grafana will fill in missing values according to the interval
-     fillvalue can be either a literal value, NULL or last; last will fill in the last seen value or NULL if none has been seen yet
+     fillvalue can be either a literal value, NULL or previous; previous will fill in the previous seen value or NULL if none has been seen yet
 - $__timeGroupAlias(column, '5m'[, fillvalue]) -> CAST(ROUND(DATEDIFF(second, '1970-01-01', column)/300.0, 0) as bigint)*300 AS [time]
 
 Example of group by and order by with $__timeGroup:

public/app/plugins/datasource/mysql/partials/query.editor.html

@@ -55,7 +55,7 @@ Macros:
 - $__unixEpochFilter(column) ->  time_unix_epoch > 1492750877 AND time_unix_epoch < 1492750877
 - $__timeGroup(column,'5m'[, fillvalue]) -> cast(cast(UNIX_TIMESTAMP(column)/(300) as signed)*300 as signed)
      by setting fillvalue grafana will fill in missing values according to the interval
-     fillvalue can be either a literal value, NULL or last; last will fill in the last seen value or NULL if none has been seen yet
+     fillvalue can be either a literal value, NULL or previous; previous will fill in the previous seen value or NULL if none has been seen yet
 - $__timeGroupAlias(column,'5m') -> cast(cast(UNIX_TIMESTAMP(column)/(300) as signed)*300 as signed) AS "time"
 
 Example of group by and order by with $__timeGroup:

public/app/plugins/datasource/postgres/partials/query.editor.html

@@ -55,7 +55,7 @@ Macros:
 - $__unixEpochFilter(column) ->  column >= 1492750877 AND column <= 1492750877
 - $__timeGroup(column,'5m'[, fillvalue]) -> (extract(epoch from column)/300)::bigint*300
      by setting fillvalue grafana will fill in missing values according to the interval
-     fillvalue can be either a literal value, NULL or last; last will fill in the last seen value or NULL if none has been seen yet
+     fillvalue can be either a literal value, NULL or previous; previous will fill in the previous seen value or NULL if none has been seen yet
 - $__timeGroupAlias(column,'5m') -> (extract(epoch from column)/300)::bigint*300 AS "time"
 
 Example of group by and order by with $__timeGroup: