.bash_prompt: Avoid double-escaping ANSI codes

Fixes mathiasbynens#399 and closes mathiasbynens#402.

.bash_prompt

@@ -91,30 +91,30 @@ fi;
 
 # Highlight the user name when logged in as root.
 if [[ "${USER}" == "root" ]]; then
-	userStyle="\[${red}\]";
+	userStyle="${red}";
 else
-	userStyle="\[${orange}\]";
+	userStyle="${orange}";
 fi;
 
 # Highlight the hostname when connected via SSH.
 if [[ "${SSH_TTY}" ]]; then
-	hostStyle="\[${bold}${red}\]";
+	hostStyle="${bold}${red}";
 else
-	hostStyle="\[${yellow}\]";
+	hostStyle="${yellow}";
 fi;
 
 # Set the terminal title to the current working directory.
-PS1="\[\033]0;\w\007\]";
-PS1+="\[${bold}\]\n"; # newline
-PS1+="\[${userStyle}\]\u"; # username
-PS1+="\[${white}\] at ";
-PS1+="\[${hostStyle}\]\h"; # host
-PS1+="\[${white}\] in ";
-PS1+="\[${green}\]\w"; # working directory
+PS1="\033]0;\w\007";
+PS1+="${bold}\n"; # newline
+PS1+="${userStyle}\u"; # username
+PS1+="${white} at ";
+PS1+="${hostStyle}\h"; # host
+PS1+="${white} in ";
+PS1+="${green}\w"; # working directory
 PS1+="\$(prompt_git \"${white} on ${violet}\")"; # Git repository details
 PS1+="\n";
-PS1+="\[${white}\]\$ \[${reset}\]"; # `$` (and reset color)
+PS1+="${white}\$ ${reset}"; # `$` (and reset color)
 export PS1;
 
-PS2="\[${yellow}\]→ \[${reset}\]";
+PS2="${yellow}→ ${reset}";
 export PS2;