Added compiler directives as necessary (adhering to the same or similar symbols as those used in the source for FSharp.Core) and implemented small bits of missing functionality in order to get ExtCore to compile for the portable Profile47 target.
Some additional, minor changes need to be made to the project files before these changes can be merged into 'master'; we need to be able to compile for various target profiles using a single project file.
Reverted changes to project files for now. I'll add additional build configurations with the necessary settings for portable projects later.
Clean up ExtCore.fsproj to remove some old build configurations and add explicit version targeting for FSharp.Core.
Modified ExtCore project file so it targets the .NET 4.0 Client Profile instead of the Full Profile (no other changes are needed for this since none of the ExtCore code was using functionality only available in the Full profile).
Implemented new functions in the Array.Parallel module: max, maxBy, min, minBy, sum, sumBy.