v0.4.0

ending position information (#22)

* logging metadata information of processing

1. Added stdout message to be processed by invoking utility.
2. Better error handling mechanism and subsequently logging the error
situation for given file on stout.

Note: where messages are printed with `log` it will print it to
`stderr`. `fmt.println` and its other version will print the message to
`stdout`

* ending poisition information

Added ending line number and column number information for each node.