Some preparation work for new platform support.

- Added a "PSP" compile-time define to clean up some compile time checks (replaced !WIN32 && !LINUX && !IOS with PSP) 
-- Wil, I am aware that this is redundant with the PSPENV variable you introduced recently, I think we can clean that up easily
-- This looks like lots of changes, but most of the time I just moved some blocks here and there
-- tested on VC 2010, PSP, and a bit of NDK
-- I might have broken maemo, iOS, or Linux compilation, can you guys check?
- Fixed some warnings reported by NDK
- NDK still does not compile because recent boost additions (mutex, etc...) are apparently not supported

projects/mtg/src/WCachedResource.cpp

@@ -134,8 +134,7 @@ unsigned long WCachedTexture::size()
     if (!texture) return 0;
 
     unsigned int pixel_size = 4;
-#if defined WIN32 || defined LINUX || defined IOS
-#else
+#if defined(PSP)
     pixel_size = JRenderer::GetInstance()->PixelSize(texture->mTextureFormat);
 #endif
     return texture->mTexHeight * texture->mTexWidth * pixel_size;