add highlight from brew and hl command

hl command accepts syntax type and optionally a filename as arguments.
If a filename is given, it will syntax highlight the file and place the
contents on the clipboard. If no file is given, it will use the contents
of the clipboard.

Brewfile

@@ -16,6 +16,7 @@ install macvim --override-system-vim
 install reattach-to-user-namespace
 install tmux
 install zsh
+install highlight
 
 # gitsh
 tap thoughtbot/formulae

zsh/functions.zsh

@@ -118,3 +118,14 @@ function gi() {
 function gci() {
     npm install --save-dev grunt-contrib-"$@"
 }
+
+# syntax highlight the contents of a file or the clipboard and place the result on the clipboard
+function hl() {
+    if [ -z "$2" ]; then
+        src=$( pbpaste )
+    else
+        src=$( cat $2 )
+    fi
+
+    echo $src | highlight -O rtf --syntax $1 --font Inconsoloata --style moria --font-size 24 | pbcopy
+}