Faster dep resolution

[sc0ttj]

FYI, getting much faster dep resolution is not gonna be too hard, cos Pkg list_deps func has some bugs and bad code - very inefficient .. and get_pkg_name() is probably over-used..

It loops over duplicates lots of times, cos the code to remove the duplicates (IIRC) is broken.

The logic is also basic, and could be improved - the code that generates the dep tree in PPM is where I wanted to look for ideas..

Also the find_deps function, which splits the list form list_deps into 2 lists (installed or not) is also slow .. just cos the code is basic, not cos it does anything clever...