[sil_ipa] Add subscript numerals to _ rota

[darcywong00]

Fixes #2401

This adds subscript numerals to the underscore _ rota

e.g.

Character	Sequence
₃	3_
3̠	3__
3̞	3___
3̙	3_____
3̧	3______
3̠	3_______

(update)
When options are set to 'before', the sequence

Character	Sequence
₃	_3

Rota still uses "_" after.

[LornaSIL]

So, it looks like you intentionally didn't try to make it work differently when the options are changed.

[darcywong00]

So, it looks like you intentionally didn't try to make it work differently when the options are changed.

At first I was going to follow the 'before' and '' options, but then it seemed odd for a rota.
I can try going back to options

[darcywong00]

OK, I've updated the options rules to convert subscript numerals with U+0320 since underscore _ automatically converts to combining minus sign below U+0320.

For 'before' options, _3 outputs ₃; and type 3_ to get to the rota 3̠.

For 'after' options, 3_ outputs ₃, ₃_ gets to the rota 3̠

[LornaSIL]

I don't think we want the sil_ipa.php file in the welcome folder. The one in the help is the correct location.

[darcywong00]

I don't think we want the sil_ipa.php file in the welcome folder. The one in the help is the correct location.

Good catch. I updated the help/ file and removed the extra one.

[LornaSIL]

LGTM