Implementation of DateTime, additional Regex methods and more

Hi Zach,

As the title says, I implemented almost complete versions of DateTime and TimeSpan with working unit tests.

I also cleaned up a bit my previous implementation of Enumerators for imperative collections (ResizeArray, Dictionary, MatchCollection...), added more expression replacements to the Regex module and exposed a couple of things which I need for the HTML extensions: Async.protectedCont and WebRequest.Url. I hope this is fine. 

I added a line to CommonOperators.fs to fix issue #111 too.

Please have a look when you have time and tell me what you think.

Cheers!
Alfonso
Hi Zach! Thanks a lot for reviewing the code and sorry for replying late. I was in the middle of a big refactoring of the imperative collections and didn't want to submit anything until the code was clean.

You are absolutely right! I didn't take that into account. I've removed DateTime.Now and DateTime.UtcNow from all the tests except for the two checking specifically these properties. As I'm checking just the hour part in most of the cases there should be no problem, but it's true that in some situations like the hour boundary you mention they can make the build fail. As it's not very difficult to get the current time in JS, we can just comment out these two tests if you prefer. Another idea is to call a couple of times DateTime.Now with Async.Sleep in between so we can just check if both calls differ in the appropriate number of seconds. On a different note, I noticed that some tests are not working properly in Jint so I commented them out, but the generated JS works fine in the browser.

BTW, in my new pull request I have modified a bit the FunScript.Seqs module to centralize the enumeration of the imperative collections, as most of them didn't force a coercion before calling the standard methods (GetEnumerator, MoveNext...) and it was complicated to deal with all of them. Beforehand, I was inserting the enum generator in the JS object but I removed that to prevent having too many hacky solutions and also to try to follow your coding style. Please have a look when you have time and tell me if you agree with the modifications.

I'm preparing a presentation to use it as a sales pitch for FunScript. I hope you'll like it :)

As usual, thanks a lot for all your work!