Proposed function: format.pronounce_currency()

[ChanceNCounter]

Larger undertaking than it sounds, but will be easier with pronounce_digits() (#130/#150).

Reason it's a larger undertaking than it sounds:

$236.58 (en-us)
colloquially: "two thirty six fifty eight"
unambiguous: "two thirty six and fifty eight cents"
formal: "two hundred thirty six dollars and fifty eight cents"
NOT: "two hundred thirty six fifty eight"

$236,580
colloquially, in financial discussion: "two thirty six five eighty"
usually: format.pronounce_number(236580, lang='en-us') (don't ask me why big numbers get formal, but they do)
possibly: "two hundred thirty six thousand five hundred eighty dollars [exactly/even]"
NOT: "two thirty six five eighty dollars"