Make all aliases optional (a la plugins)

This continues a pattern that was introduced in ffa45b0 and refined
further in later commits.  This enables all aliases by default, but can
be disabled by any user if they remove the appropriate
aliases/enabled/*.bash file.

aliases/available/general.aliases.bash

@@ -0,0 +1,73 @@
+#!/bin/bash
+
+# List directory contents
+alias sl=ls
+alias ls='ls -G'        # Compact view, show colors
+alias la='ls -AF'       # Compact view, show hidden
+alias ll='ls -al'
+alias l='ls -a'
+alias l1='ls -1'
+
+alias _="sudo"
+
+if [ $(uname) = "Linux" ]
+then
+	alias ls="ls --color=always"
+fi
+
+alias c='clear'
+alias k='clear'
+alias cls='clear'
+
+alias edit="$EDITOR"
+alias pager="$PAGER"
+
+alias q="exit"
+
+alias irc="$IRC_CLIENT"
+
+alias rb="ruby"
+
+# Pianobar can be found here: http://github.com/PromyLOPh/pianobar/
+
+alias piano="pianobar"
+
+alias ..='cd ..'        # Go up one directory
+alias ...='cd ../..'    # Go up two directories
+alias -- -="cd -"       # Go back
+
+# Shell History
+alias h='history'
+
+# Tree
+alias tree="find . -print | sed -e 's;[^/]*/;|____;g;s;____|; |;g'"
+
+# Directory
+alias	md='mkdir -p'
+alias	rd=rmdir
+
+function aliases-help() {
+  echo "Generic Alias Usage"
+  echo
+  echo "  sl      = ls"
+  echo "  ls      = ls -G"
+  echo "  la      = ls -AF"
+  echo "  ll      = ls -al"
+  echo "  l       = ls -a"
+  echo "  c/k/cls = clear"
+  echo "  ..      = cd .."
+  echo "  ...     = cd ../.."
+  echo "  -       = cd -"
+  echo "  h       = history"
+  echo "  md      = mkdir -p"
+  echo "  rd      = rmdir"
+  echo "  editor  = $EDITOR"
+  echo "  pager   = $PAGER"
+  echo "  piano   = pianobar"
+  echo "  q       = exit"
+  echo "  irc     = $IRC_CLIENT"
+  echo "  md      = mkdir -p"
+  echo "  rd      = rmdir"
+  echo "  rb      = ruby"
+  echo
+}