evolve: add selector for trouble types This patch adds command line flags to select the kind of troubles to solve. Before this patch evolve was solving any kind of troubled. With this patch evolve --all and evolve --rev can be configured to only solve only some type of troubles (divergent, bumped or unstable). To give this choice to the user we add three new command line flags to the evolve command: --bumped, --divergent and --unstable.