Bash: the bashrc in the home directory should usually source the system one

Bash is a bit strange here in that there isn't anything enforced at the
system level. User's can override everything. Good to make sure we pick
up the system defaults first.
Tmux/Vim: Don't delay after escape in tmux so vim works more snappily
Vim: colorscheme tweaks, nicer window borders on 256-colour terminals
Removed TERM override. It was a bad idea - it confuses some applications

Some applications were not clearing the screen or using the alternative
buffer correctly.
Bash: less and ls colour tweaks