.emacs: Removed some settings to make UI simpler.
.emacs: Some trivial changes.

- Ignore buffers which have no file in list-buffers.
- Ignore case during searching.
- Save file before compilation without asking.
- Use text-mode as default major mode.
- Delete customization of org-startup-folded.
.bashrc: Some trivial changes.

- Added environmental variable "TZ".
- Added alias "w3m" to set default command line options.
- Modified PROMPT_COMMAND to print title bar correctly under screen.
.screenrc: Deleted customization of termcapinfo.