Improved premake5 file sample

Added some docmumentation, fixed indentation and use groups to hide
external libraries in a folder.

premake5.lua → premake5.sample.lua

@@ -1,3 +1,6 @@
+-- Here's a sample file to show how to use prelude. You can directly copy it to
+-- premake5.lua to get ready to work with some libraries or tweak it.
+
 local prelude = require "prelude"
 local portaudio = require "prelude.libraries.portaudio"
 local physfs = require "prelude.libraries.physfs"
@@ -8,9 +11,13 @@ workspace "Your Project here"
     configurations {"Debug", "DebugOpt", "Release"}
     location "build"
 
+    -- TODO: Decide about whether keeping the group usage here or include it in
+    -- use's call.
+    group "External"
     glm:use "None"
     portaudio:use "SharedLib"
     physfs:use "SharedLib"
+    group ""
 
     -- I'll also try to have a common core system to factorize some programming
     -- elements together.
@@ -25,10 +32,10 @@ workspace "Your Project here"
         files {"include/main/**.hpp", "src/main/**.cpp"}
         includedirs {"include"}
         links {"Core"}
-		
-		-- TODO : issues at link on VS2015. Does it happen at home?
-		-- Need to manually check "Link Library Dependencies" every time.
-		prelude.link_against_modules {portaudio, physfs, glm}
+        
+        -- TODO : issues at link on VS2015. Does it happen at home?
+        -- Need to manually check "Link Library Dependencies" every time.
+        prelude.link_against_modules {portaudio, physfs, glm}
 
-        prelude.base_project_settings()
+    prelude.base_project_settings()