emacs: remove git-blame package

must have installed it without really thinking just because it had git
in the name. I've never used it, I use magit-blame-mode instead
emacs: don't use next/previous-error for flycheck

it might get in the way of navigating grep matches sometimes
emacs: don't use ggtags navigation mode

ggtags uses a regular grep/compilation mode buffer for results, but also
enables a special navigation mode with different keybindings.

I prefer the regular compilation-mode bindings. And it makes sense to
have consistent bindings when navigating grep results and tag
results. So prevent it from enabling this mode.

Also make ggtags not abbreviate filenames in its results by default.