[WIP] Suppress compiler warnings.

Disable a few Visual Studio warnings:

C4244: conversion from 'type1' to 'type2', possible loss of data
C4267: conversion from 'size_t' to 'type', possible loss of data

Considering the GCC/Clang counterpart '-Wconversion'
(https://gcc.gnu.org/wiki/NewWconversion) is not covered by '-Wall', it
seems to make more sense to disable these two warnings in Visual Studio,
rather than fixing these warnings with hundreds of static_cast<> in the
source code.

build3/premake4.lua

@@ -6,10 +6,15 @@
    		osversion.majorversion, osversion.minorversion, osversion.revision,
    		osversion.description))
 
-
-	-- Multithreaded compiling
 	if _ACTION == "vs2010" or _ACTION=="vs2008" then
-		buildoptions { "/MP"  }
+		buildoptions
+		{
+			-- Multithreaded compiling
+			"/MP",
+			-- Disable a few useless warnings
+			"/wd4244",
+			"/wd4267"
+		}
 	end
 
 	act = ""