[Uim] Renaming of filenames

[TOKUNAGA Hiroyuki]

There are some inappropriate filenames in uim.

To improve readability, we should rename them.

At the beggining, I decided to change the name of uim/context.h. Now
context.h includes many internal definitions of libuim, so IMO uimint.h
(or uim-int.h) would be appropriate. (xxxint.h is used in Cairo.)

If there's no objection, I'll rename that in tommorow.


Regards,

-- 
TOKUNAGA Hiroyuki
tkng at xem jp