[Mediawiki-i18n] Extension to wrap certain characters in a span

[Nick White]

In case the previous description was unclear, below is an example of
what the extension does:

original wikitext:

  Hello this is English, τηφσ ισ θοδδω, and back to English again.

processed to become this:

  Hello this is English, <span lang="grc">τηφσ ισ θοδδω,</span> and back to English again.

The span attributes can be configured with a global configuration
variable, as can the range of characters that should be enclosed in
it.

Again, any response would be very welcome.

Nick