Disassembly view redesign

This redesigns the disassembly view and gives it more features. 

Changes:
-change the cursor with the mouse or with the keyboard
-displays symbols on the left and in opcode arguments
-press tab to toggle displaying of symbols
-click on the highlighted line to toggle a breakpoint at that position
-press right to follow a branch and left to go back a level
-added a few more default symbols to the symbol map

And a few minor things.

![psp2](https://f.cloud.github.com/assets/4809758/706052/f090cb04-dde2-11e2-8be6-4af5ab488623.png)