aliases/general: minor fixes

- Don't define some aliases if the target isn't installed, use _command_exists to check instead of `type` and `which`.
- Use `$EDITOR` for the editor for aliases about editing, excep the `sudo` ones because maybe you want those specifically?
- Fix `ls` aliases to match their common definitions (-A instead of -a: don't show '.' and '..' when displaying hidden files).

aliases/available/general.aliases.bash

@@ -12,15 +12,15 @@ fi
 # List directory contents
 alias sl=ls
 alias la='ls -AF'       # Compact view, show hidden
-alias ll='ls -al'
-alias l='ls -a'
+alias ll='ls -Al'
+alias l='ls -A'
 alias l1='ls -1'
 
 alias _="sudo"
 
 # Shortcuts to edit startup files
-alias vbrc="vim ~/.bashrc"
-alias vbpf="vim ~/.bash_profile"
+alias vbrc='${EDITOR:-vim} ~/.bashrc'
+alias vbpf='${EDITOR:-vim} ~/.bash_profile'
 
 # colored grep
 # Need to check an existing file for a pattern that will be found to ensure
@@ -30,10 +30,8 @@ then
   alias grep='grep --color=auto'
 fi
 
-if which gshuf &> /dev/null
-then
-  alias shuf=gshuf
-fi
+_command_exists gshuf \
+	&& alias shuf=gshuf
 
 alias c='clear'
 alias k='clear'
@@ -52,8 +50,8 @@ alias py='python'
 alias ipy='ipython'
 
 # Pianobar can be found here: http://github.com/PromyLOPh/pianobar/
-
-alias piano='pianobar'
+_command_exists pianobar \
+	&& alias piano='pianobar'
 
 alias ..='cd ..'         # Go up one directory
 alias cd..='cd ..'       # Common misspelling for going up one directory
@@ -65,17 +63,16 @@ alias -- -='cd -'        # Go back
 alias h='history'
 
 # Tree
-if [ ! -x "$(which tree 2>/dev/null)" ]
-then
-  alias tree="find . -print | sed -e 's;[^/]*/;|____;g;s;____|; |;g'"
-fi
+_command_exists tree \
+	|| alias tree="find . -print | sed -e 's;[^/]*/;|____;g;s;____|; |;g'"
 
 # Directory
 alias md='mkdir -p'
 alias rd='rmdir'
 
 # Shorten extract
-alias xt="extract"
+_command_exists 'extract' \
+	&& alias xt="extract"
 
 # sudo editors
 alias svim="sudo vim"