PCL support (see #15).

Consequently, ParseException no longer supports serialization, regular expressions are no longer compiled, and an extension method has been implemented to support treating a string as IEnumerable<char> (which is not possible in WinRT's portable subset).

Also updated NuGet.exe and the build script to produce a working PCL NuGet package.
Add XDelimitedBy for better error message on failure.
Make error message from AssertParser more informative (show expectations in the error)
Add parsers for some primitives and test scenario AssemblerParser to demonstrate usage of that primitives.
Update README.md
Merge remote-tracking branch 'upstream/master'
Add ability to set minimum number of repeats.

Added feature to set both a minimum and maximum number of repeats.
Improving Error Message

Improved parsing error message to improve clarity.
Merge pull request #41 from a-h/master

Add Feature to Set Minimum and Maximum Repeat Count