Merge pull request #1 from arendjr/master

Update from original
Add plural form extraction support

Change the content of messages[string] value of each extractor to a more complex form registering singular & plural form when present. message still default on "".

Update the .pot construction to write

msgid: definition.singular
msgstr: definition.message (remember, "" by default)

or

msgid: definition.singular
msgid_plural: definition.plural
msgstr[0]: definition.message (remember, "" by default)

some work needed to factorize the logic and keep it DRY in extractors.
use type of to check if undefined
factorize the get messages part
More comments & explicit variables
Merge pull request #14 from JSteunou/master

Add plural form extraction support