fix for evil-mode in terminal and making vim emulation more consistent

Hi bbatsov,

evil-mode in the terminal has an issue where if you type esc-key really fast it is translated as meta-key. This is obviously super bad and makes using evil-mode in the terminal not useful. Setting it to 0 fixes this issue and the meta key still works.

Also vim matches _ by default as part of a word, so I added behavior for evil-mode to act more like vim.