Add inline comments to erlydtl parse tree.
New api for sources parser: add translators comments extraction.

Old API still available: new api's responses are converted to
old ones.
There is phrase information fields added, which we currently don't
extract, like 'msgid_plural', 'context'. Will be implemented later.
Update NEWS
Merge branch 'pu-translators_comment' (close #152, fixes #127)
Fix deps in rebar configs.