+ Print stack trace on "task_error" + Current transform/filter customized debug message for each filter + Now filters can handle either a field named `ext` or `extension` with the new file extension for target according to the current filter.
+ Print stack trace on "task_error"
+ Current transform/filter customized debug message for each filter
+ Now filters can handle either a field named `ext` or `extension`
with the new file extension for target according to the current filter.

bucaran/fly,lukeed/taskr,lukeed/taskr,lukeed/taskr