[shell/vim] Disable beeping and window flashing

Both `vim` and the `terminal` beep or flash their windows if an error
occurs. This commit disables that behavior as it is really annoying.

See also:

 * http://vim.wikia.com/wiki/Disable_beeping
 * http://ss64.com/bash/syntax-inputrc.html
[shell] Remove `npme` alias

In my case, the European `npm` mirror does not provide a significant
improvement over the default.
[vim] Add `editorconfig` plugin

See also: http://editorconfig.org/