add checked expressions to compiler API
fixes for big expressions and stress testing
merge master
fix test
fixes to scale to large pattern matching and sequence expressions
stylistic cleanup and add FSharpExpr.Type
add documentation
add better error handling and stress test on FSharp.Core
fixes for stress test on FSharp.Core
documentation and fix for 'let'
ad documentation file
reduce test times on appveyor (to avoid timeouts)
update for code review
Merge pull request #241 from quasilord/exprs2

add checked expressions to compiler API