.zshrc: remove code for dumb terminals
.elisp/org-mode: rewind to latest release

org-export is broken in HEAD.
.zshrc: compact prompt code
.zshrc: remove EDITOR-related suffix aliases
.gitconfig: enable grep.lineNumber
.gitconfig: define pretty.lg

To avoid cluttering up alias.lg.
.gitconfig: turn off all advise

I'm an expert user, and it's distracting.