Add some compose sequences for the Afnor French layout

This key is used to emit letters from European languages with latin languages, and is specified in the standardized French keyboard (NF Z71-300, defined by the French office for standardisation AFNOR)

References

References and related work can be found here (in French): http://norme-azerty.fr/ and there are also a couple of press releases in English:

• by Aalto university, who collaborated on defining the layout
• on motherboard.vice
• on BBC World Service's The Newsroom (audio, at 19:09-21:00)

This is the proposed “Eu level”, i.e. the layout when activating the newly defined dead key:

• I have converted the key combinations and placed them into the Compose file right after the other French keys that are also used in this keyboard (most notably dead_greek).
• The definition of the keycode to be used for dead_latin is at xorg/proto/xorgproto!60
• There is no corresponding bug that I could find on bugs.freedesktop.org − this ancient bug on creating the greek dead key seems related.