libseed-list js extensions for native modules

[Jonatan Liljedahl <lijon kymatica com>]

The gi_importer tries to import extensions/name.js by evaluating 
"imports.extensions.name". It would be nice if this also worked for 
native modules, I imagine it to be quite common that you write a module 
with core parts in C and some high-level stuff in js.

The question is, how should this be handled regarding searchpaths etc?

If your module is installed in /usr/local/lib/seed, then you probably 
installed the extension js in /usr/local/share/seed/extensions, and 
imports.extensions would be the right thing.

But what happens if your module is installed somewhere else? It should 
probably start with the same dir as the native module, then go on with 
imports.searchPath, and if the file is found call 
seed_importer_handle_file() on it..

BTW, what happens if you have 'extensions' folder in more than one 
search path? will extensions.foo search for 'foo' in all of those or 
only the first match for 'extensions'? Just doing a 'imports.extensions' 
will of course create only one dir_importer for that folder, hiding 
possible 'extensions' folders later in the searchpath. I don't know if 
this is a good thing...

/Jonatan