Deobfuscation of Minecraft's internal exception types

Enables deobfuscation of Minecraft's internal exception types like net.minecraft.command.CommandException

Before if a mod had something like:
```
try { ... }
catch (net.minecraft.command.CommandException e) { ... }
```
it wouldn't be deobfuscated and CommandException would still be the obfuscated aq (1.4.7)

similarly with a throws declaration:

```
void doSomething() throws net.minecraft.command.CommandException { ... }
```

would look like

```
void doSomething() throws aq { ... }
```

Although this seemingly had no impact in running the mod deobfuscated (I guess Java just uses this for compilation, IDK.)

I was trying to track something down with an interaction with Mystcraft 0.10.1 for a practical example (com.xcompwiz.mystcraft.command.CommandTPX exhibits both problems.)