add scons extra suffix option

makes it possible to add a custom extra suffix to the base filename of
all generated binary files.

example :
scons p=windows extra_suffix=yourBranchName
or
scons p=windows bits=32 extra_suffix=v20150401_1642
or
scons p=windows extra_suffix=msvc2010_git20150401

SConstruct

@@ -121,6 +121,7 @@ opts.Add("LINKFLAGS", "Custom flags for the linker");
 opts.Add('disable_3d', 'Disable 3D nodes for smaller executable (yes/no)', "no")
 opts.Add('disable_advanced_gui', 'Disable advance 3D gui nodes and behaviors (yes/no)', "no")
 opts.Add('colored', 'Enable colored output for the compilation (yes/no)', 'no')
+opts.Add('extra_suffix', 'Custom extra suffix added to the base filename of all generated binary files.', '')
 
 # add platform specific options
 
@@ -176,6 +177,9 @@ if selected_platform in platform_list:
 		env = env_base.Clone()
 
 	env.extra_suffix=""
+	
+	if env["extra_suffix"] != '' :
+		env.extra_suffix += '.'+env["extra_suffix"]
 
 	CCFLAGS = env.get('CCFLAGS', '')
 	env['CCFLAGS'] = ''