Correct misspelling of 'referenceable'

That has to be a bug in Wiktionary, see grammar:

While a terminal silent -e is usually dropped when adding a suffix beginning with a vowel, which is followed by -able, the -e is not dropped when adding -able if the root ends with a soft -ce and -ge, as in replaceable and changeable, so that these are not misinterpreted as hard ‘c’ or ‘g’ sounds.

Other examples:

• noticable: "Common misspelling of noticeable."
• replacable: "Common misspelling of replaceable."
• enforcable: "Common misspelling of enforceable."
• facable: not even listed misspelling of faceable
• servicable: not even listed misspelling of serviceable
• tracable: not even listed misspelling of traceable
• changable: "Common misspelling of changeable."
• managable: not even listed misspelling of manageable

So while it might be a common misspelling, it remains a misspelling.
Though it might be more obvious to native speakers of some romanic languages than to English native speakers, because spelling rules are stricter (and bear more consequences to pronunciation).
Leaving a note on the Wiktionary's talk page and keeping this issue open.

I can't find evidence of 'referencable' being correct, and English grammar, common sense and the spelling of other adjectives with the same root ending point in the direction that only 'referenceable' is correct English, so here's a patch.

If still in doubt we could possibly wait until Wiktionary has decided on this issue, but IMHO it's quite obvious and we know that 'referenceable' certainly is correct.

Leaving this at 'normal' priority even though it has no repercussions for the simple reason that it's getting harder to fix the spelling, the more SelectionInterface is implemented - and there is already at least one patch around implementing it.

#3: referenceable_spelling-2020405-3.patch queued for re-testing.

Discussion on Wiktionary: Rfv, Tea room and grammar evidence clearly point to referencable (without -e-) being a mere misspelling, not an alternative spelling of referenceable (with -e-).
While the Rfv (Request for verification) on Wiktionary will only be finished by Juli 1st, the direction should be clear enough to correct this before API freeze.

New patch.
Major because API freeze is coming closer, and it is getting bigger and bigger...

Referencable now has been marked as a misspelling in Wiktionary.
One more reason to move this forward, even if technically we have more ambitious issues to fix until July 1. Finally, responsibility for a correct language is an aspect of "Do well, do good".
Anybody wanting to do a review? Probably more a review of the Wiktionary discussions and its results would be needed than a review of this unsurprisingly simple patch.

So adding tag.