Document why MessageFormat needs a successor

[stasm]

The group's charter has a few hints but I think it would be valuable to document the shortcomings of MessageFormat, and the reasons why we think it needs a successor.

The Message Format Working Group (MFWG) is tasked with developing an industry standard for the representation of localizable message strings to be a successor to ICU MessageFormat. MFWG will recommend how to remove redundancies, make the syntax more usable, and support more complex features, such as gender, inflections, and speech. MFWG will also consider the integration of the new standard with programming environments, including, but not limited to, ICU, DOM, and ECMAScript, and with localization platform interchange. The output of MFWG will be a specification for the new syntax, which is expected to be on track to become a Unicode Technical Standard.

[romulocintra]

@mihnita just assigned you this issue :)

[zbraniecki]

@mihnita I'd be interested in supporting you in this. My angle is two fold:

1. I was involved in the evaluation of MessageFormat for Mozilla needs, which resulted in Fluent
2. I wrote the Fluent vs MessageFormat comparison

In particular, I'm aware that (2) is not precise and in multiple places overstates the shortcomings of MF, so I'd like to correct that as part of work on this document.

[romulocintra]

Closed By #84