Should also fix void-function/void-variable errors caused by evil-magit
depending on the newer version of magit (#1174).
Also introduces a redesign of the SPC g prefix.
Loading magit-blame immediately after git-timemachine is premature, only
one command uses magit-blame (git-timemachine-blame), so we defer it
until that command is called (also, it makes more sense to be in the
emacs/vc module, than tools/magit).
Remove +vcs|enable-smerge-mode-maybe, as this is already automatically
enabled when current file is has merge conflicts.
Moved +hydra-smerge to autoloads file, and add it to smerge-mode-hook.