-Screwed around with SSE2.

-Added ReleaseSSE2 as a build target.
-LL_VECTORIZE is silly and breaks things...
-Small little tweaks.

I have not tested if the cmake alterations work under linux and darwin. Hollar if broken.

indra/llmessage/partsyspacket.cpp

@@ -144,6 +144,8 @@ LLPartSysCompressedPacket::LLPartSysCompressedPacket()
 		mData[i] = '\0';
 	}
 
+	mNumBytes = 0;
+
 	gSetInitDataDefaults(&mDefaults);
 }