Added a bunch of new aliases and urxvt TERM value.

.bash_aliases:
- Added a bunch of shorthands for most used commands;
- Organized the file a bit.

.bashrc:
- TERM is defined to "rxvt" in case we're using Debian's
  rxvt-unicode-256color package, so that remote hosts won't complain
  about a not supported terminal;
- Moved some aliases to .bash_aliases.