Highlight disabled breakpoints and use font sizes in more controls

Puts a previously unused icon to use to highlight disabled breakpoints in the disassembly view. Toggling them will re-enable them, and toggling a breakpoint with an enabled condition will ask for a confirmation (as they aren't as simple to recreate than those without a condition).
Also makes the memory viewer and register list use the configurable font size.
![psp8](https://f.cloud.github.com/assets/4809758/773706/e300c6b0-e940-11e2-87fa-e156b472b0bc.png)