[PATCH weston 0/3]Rework libweston versioning take 3

[Emil Velikov]

Hi all,

Here is hopefully the final take on the series of the topic in question. 
The changes:

 - Reworked the README, elaborating on why and how to use 
REQUIRE_LIBWESTON_API_VERSION (what to write in your configure), how to 
avoid forward compat and misc working improvements.

 - There is a comment about the strange use of LT_VERSION_INFO 
(Quentin) and we no longer have link errors (there was a typo on my end)

 - Dropped "libweston: do not add libweston-$version to the Cflags" in 
favour of "libweston: remove pkgincludedir variable from libweston.pc"

 - Dropped "libweston: do not use weston version in libweston.pc". 
Around the time of release we could unify the version numbers (i.e. 
reuse the weston ones in libweston).

I believe I've covered everything, but if something is a bit off please 
let me know.

Regards,
Emil