Converted Chronic to a portable library

[eugenpodaru]

I've converted Chronic to a portable library.

To make it compile I had to remove the RegexOptions.Compiled flag used when creating regular expressions as it is not supported in SL and WP.

I also changed Math.Truncate with Math.Floor in two places as Math.Truncate is missing from SL and WP. Floor and Truncate behave in the same way for positive numbers, which was the case in those two places.

I want to use the library in a SL project, so that's why I did this. If you accept the pull request, and push it to nuget, I will get it from there. Otherwise I will just use the binaries compiled from my branch.

Regards,
Eugen

[robertwilczynski]

Thanks for the PR Eugene - I will try to find some time and think how to best integrate your changes and still keep the regex compilation (will test if it has any real benefits). Maybe a second, portable, nuget will be the way to go.

[eugenpodaru]

Here you can find an article about RegexOptions.Compiled http://blog.codinghorror.com/to-compile-or-not-to-compile/. The only scenario where it may count is when you have a lot of expressions to parse in a loop, which is a valid scenario. So maybe it would be better to have two versions. I leave this to you to decide. For now I use the modified library from a private repository, but if you decide to put it on nuget, i will use the official one.