update targets to build PCL with 3.4.0 and 3.2.7

Source code alignment

Fix fsharp#304

Fix fsharp#299

Build back version of FSharp.Core 4.3.0.0 and 2.3.0.0, to include fix…

…es removing GetObjectData methods from exception definitions

Fix fsharp#283: build 2.3.5.0 FSharp.Core PCL assembly

Fix fsharp#196

Fix fsharp#282

Merge pull request fsharp#277 from enricosada/vs2013_templates

add visual studio 2013 fsharp project template

update signed dlls