fix .bash_prompt

* tty: Title escape sequence is only used on pts. tty do not support them, leading to a garbled prompt.
* same functionality without using PROMPT_COMMAND. Now it's available for other purpose.
fix colors for tty

 * .bash_prompt: do not modify the TERM for tty. It should stay as "linux".
 * .colors: modify color tones for tty (framebuffer only?). DarkBlue which is used for directories was nearly unreadable.
 * .vimrc: now also for tty