Matches strings within a gettext call. Covers the following examples:
- gtxt('i am in single-quotes')
- gtxt('i have ' an escaped single-quote within single-quotes')
- gtxt('i have a "double-quote" in single-quotes')
- gtxt("i am in double-quotes")
- gtxt("i am in double-quotes with single 'quotes'")
- gtxt('i have an escaped double-quote " within double-quotes')
Note that gettext has been aliased to gtxt here, so change it to whatever alias you're using. I also have a lazy version of gettext, hence the optional lazy_ portion, which can be deleted.