doc: bumped version to 0.15.

style: fixed coding style issues found by ngx-releng.

doc: bumped version to 0.14.

doc: version 0.13 and nginx compatibility as far as 1.9.15.

style: minor fixes.

doc: updated copyright years.

updated docs to reflect recent changes.

updated docs to reflect recent changes.

bugfix: fixed nil multi bulk replies in the reply parser.

bugfix: fixed compilation errors when DDEBUG = 1.