[Premake] Add VS2012, EnableSSE2 and "--with-c++11"

[Jorma Rebane]

This patch adds three new features to the build system:

• VS2012 project generation - premake4 now accepts "vs2012" and generates a correct solution file for VS2012.
• EnableSSE2 - automatically enables SSE2 via premake flag "EnableSSE2"; This doesn't really change anything for gcc/icc, but is crucial to enable SSE2 code generation in VS projects. Using the default feature of premake which ignores EnableSSE2 on systems that don't support it.
• "--with-c++11" - Special premake flag that passes -std=c++0x to gcc/icc. Simply pass --with-c++11 to enable C++11 features. For testing and possible migration to C++11 in the future.

I also added a new batch file that generates atlas build for VS2012. This is useful for developers who need to recompile AtlasUI.dll.

[Jorma Rebane]

Split patch, only VS2012 support for premake4

[Jorma Rebane]

Premake4 VS2012 support now part of changeset r13970

[Jorma Rebane]

Adds SSE2 to Windows build and optional C++11 build option

[Jorma Rebane]

In 13971:

Adds EnableSSE2 for Visual Studio builds on windows.
Adds optional "--with-c++11" flag for GCC/ICC builds. For possible future C++11 migration.
refs #2191

[Jorma Rebane]

In 13972:

Fixed premake4 build incorrectly ignoring vs2010 action.
fixes #2191