.emacs: Changed IME from Mozc to SKK, and shrank this file.

- Removed settings for Mozc.  Now default IME is SKK.
- Use electric-indent-mode.
- Use whitespace-mode, and removed my original settings like whitespace-mode.
- Removed settings for Japanese holidays.
- Removed redundant settings for comint-mode.
- Use SPACE for indentation except for c++-mode.
- Changed directory of document files.
- Added some useful settings for dired.
- Don't highlight mis-spell persistently in flyspell-mode.
- Use uniquify-buffer-name-style.
.bashrc: Make cache directory of ccache in /tmp.
.screenrc: Specify shell.
cgdbrc: Don't use long arrow which makes screen dirty sometimes.