Don't abort a solve if we can't read one of the feeds

Just log the exception and continue.
Make an interface conflict with its replacement
Process feeds imported with <feed>
Handle the old compile:command attribute
Added multi-arch support to the solver

Also, better OS/CPU detection and ranking in general.
Also sort implementations based on being preferred, language, country, OS, CPU and ID
Code tidying
Add from-feed attribute, if not the same as the interface
Don't get stuck looping with recursive dependencies