Add unit test for parameterized strings.
Fix bug in generation of .po comments

It was written ".#" but should have been "#." for extracted comments
Fix regex for reading gettext to be more lenient and remove extra logging

We don't distinguish between the types of comments and should allow space between
the field type and the value.

Also, the extra logging was accidentally left in and should be removed
Update test-output-7.txt to be compliant with the actual comment specification

The proper comment structure for gettext is not ".#" but "#." as seend in:

https://www.gnu.org/software/gettext/manual/gettext.html#PO-Files

The code was updated, but the test case was not.  This commit addresses that
oversight.
Add contributors section.
Update verstion to 0.4.0.
Add a note about the Twine TextMate 2 bundle.
Add reference to twine_ui.
Properly credit twine_ui.
Write all languages to the twine strings file.

We used to only write translations to the strings file that did not
match the developer language. It was done this way to try and reduce
space in the strings file and to get en-UK to pick up en changes.

This turned out to be the wrong decision. It's better to explicitly
ensure that all strings are translated in all languages, and to not
automatically pick up en string changes in other languages.

This fixes issue #29.
Add test for multiline strings in .po files
Fix parsing of .po files for multiline msgstr

It's valid for a msgstr to be broken over multiple lines, all of which
are enclosed with ".  To handle this, no longer iterate over the lines within
an item but rather apply the matching to the entire item.