Allow all interface strings to be automatically extracted, so they can be translated by the community

Problem/Motivation

Currently a number of strings are translated as a variable, for example:

$text = 'Add new !title';
if ($max >= 0) {
  $text = 'Add another !title';
}

'#value' => t($text, array('!title' => t($instance['settings']['title']))),

These strings are not extracted by template extractors such as potx.

Proposed resolution

Update the calls to t() with strings instead of variables, so the text can be translated by the community.

Remaining tasks

1. Write a patch
2. Review
3. Commit

User interface changes

None

API changes

None

Data model changes

None