Use latest TypeScript compiler version automatically

[alexfoxgill]

This small feature addresses #1284 by allowing a version wildcard in tryFindFile. When given a path containing the wildcard [v], the algorithm will search the the parent directory for subdirectories matching a regular expression which identifies digits separated by dots (e.g. 1.8)

The TypeScriptCompilerPath has been updated to use the feature:

let private TypeScriptCompilerPath = 
    @"[ProgramFilesX86]\Microsoft SDKs\TypeScript\[v]\;[ProgramFiles]\Microsoft SDKs\TypeScript\[v]\"

I have not written any tests for this method, as it is difficult to mock the filesystem, which the tryFindFile method relies on. Perhaps a configurable proxy module could be created to provide Directory.GetDirectories, Directory.Exists and File.Exists and provide override methods in test code... But I think this is overkill.

[alexfoxgill]

I've just seen another PR #1308 which seems to do this too...! The other PR has fewer far-reaching consequences so I'd probably go with that one