Adding emoticon support

Support for the following emoticons:

* :)
* :(
* :3
* ;3
* :s
* ;(
* ;)
* ;D
* :P
* xP
* :o and :O
* :D
* ^^,
* <3
* >.<
* >_<
* xD and XD
* o.0
* 0.o
* :\ and =\
* :/ and =/

Closes #260
Sprite the emoticon images
emoticons moved to CSS