Fix premake5 alpha13 warnings.

Update BUILDING.md to require premake5 alpha13

BUILDING.md

@@ -3,7 +3,7 @@ Building yojimbo
 
 ## Building on Windows
 
-Download [premake 5](https://premake.github.io/download.html) and copy the **premake5** executable somewhere in your path. Please make sure you have at least premake5 alpha 10.
+Download [premake 5](https://premake.github.io/download.html) and copy the **premake5** executable somewhere in your path. Please make sure you have at least premake5 alpha 13.
 
 You need Visual Studio to build the source code. If you don't have Visual Studio 2015 you can [download the community edition for free](https://www.visualstudio.com/en-us/downloads/download-visual-studio-vs.aspx).
 

premake5.lua

@@ -8,7 +8,7 @@ solution "Yojimbo"
     language "C++"
     platforms { "x64" }
     configurations { "Debug", "Release" }
-    if os.is "windows" then
+    if os.istarget "windows" then
         includedirs { ".", "./windows", "netcode.io", "reliable.io" }
         libdirs { "./windows" }
     else
@@ -17,7 +17,9 @@ solution "Yojimbo"
     end
     rtti "Off"
     links { libs }
-    flags { "ExtraWarnings", "FloatFast", "EnableSSE2" }
+    warnings "Extra"
+    floatingpoint "Fast"
+    vectorextensions "SSE2"
     configuration "Debug"
         symbols "On"
     configuration "Release"
@@ -61,7 +63,7 @@ project "soak"
     files { "soak.cpp", "shared.h" }
     links { "yojimbo" }
 
-if not os.is "windows" then
+if not os.istarget "windows" then
 
     -- MacOSX and Linux.
 
@@ -414,7 +416,7 @@ newaction
           os.rmdir( v )
         end
 
-        if not os.is "windows" then
+        if not os.istarget "windows" then
             os.execute "find . -name .DS_Store -delete"
             for i,v in ipairs( files_to_delete ) do
               os.execute( "rm -f " .. v )