add visual studio 2013 fsharp project template

Microsoft Visual Studio Premium 2013
Version 12.0.21005.1 REL
Microsoft .NET Framework
Version 4.5.51641

Installed Version: Premium

Visual F# 2013   06191-004-0456024-02825
Microsoft Visual F# 2013
Merge pull request #277 from enricosada/vs2013_templates

add visual studio 2013 fsharp project template
Unicode letters & operators

examples:
let ★ x = x + 5
let (|★) x y = x + y
let summ = ★ 5 |★ 5
comment about \So infix operators
apply & merge optimizations from : https://github.com/jack-pappas/fs-core-optimized , thanks to Jack Pappas
revert set.fs optimizations due complicated conflicts