build.bat : msbuild support more platforms

same way as it's done in corefx
Merge pull request #346 from Heather/patch-1

build.bat : msbuild support more platforms
Unicode letters & operators

examples:
let ★ x = x + 5
let (|★) x y = x + y
let summ = ★ 5 |★ 5
comment about \So infix operators
.sharingan.yml