Textview Scrollbar

![Screenshot](http://i.imgur.com/LSAOPxw.png)

Todo:
Move drawScrollBar to CoreLib
Move drawVLineAND to kernel
Because you can only load from pointers into A. `ld b, (0x1234)` is compiled by evaluating `(0x1234)` as if it were an expression. That is, it evaluates to 0x1234, which is too big to fit in B, an 8-bit register.