[AD] config files return from the dead

["Vincent Penquerc'h" <Vincent.Penquerch@xxxxxxxxxx>]

Title: config files return from the dead

Config files have an annoying behavior of using only one, though
they can look in several places.
Say, I have a mouse which has a particular protocol. Since this is
for all the system, obviously, I set this in /etc/allegrorc.
Now, I have two programs, both of which use a local allegro.cfg
in their directory. Even if these do not specify a mouse protocol,
the settings in /etc/allegrorc will be ignored. That is *very*
annoying.
What should be done is load every file in order (the one from/etc,
then the one from $(HOME), then the one in . (if they exist).
The entries should then replace every corresponding entry from
other files loaded earlier.
I guess it can be done really easily, as there is already an API
entry called override_config_file, which probably does what it
looks it does, though I haven't looked.
If nobody wants to code it but most people are not opposed to the
idea, I may code it some time in the future, when I get some time.

--
Vincent Penquerc'h