[O] [DEV] Bump Emacs requirement to 24.4?

[Nicolas Goaziou]

Hello,

Just to be sure, can we require Emacs 24.4 for development version
(a.k.a. Org 8.4)? As a data point, Debian stable provides it.

Also, what is the status of XEmacs support? AFAIU Org 8.3 doesn't build
on XEmacs but no one is complaining. We may as well drop it and ignore
most of "org-compat.el".

WDYT?


Regards,

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Nicolas Goaziou                                                0x80A93738