Hex support:

<RAINBOW1> -> Set message with rainbow colors
<SOLID:colorInHex> -> Set a hex color in the text
<GRADIENT:gradient> -> Set a gradient of colors

Example
<GRADIENT:2C08BA>Cool string with a gradient</GRADIENT:028A97>
<RAINBOW1>THIS IS A REALLY COOL Rainbow</RAINBOW>
<RAINBOW100>THIS IS A REALLY COOL Rainbow</RAINBOW>
<SOLID:FF0080>Cool RGB SUPPORT