Made a few lines of code easier to read.
Simplified a few test-types.
Added a test case for a method with many parameters that returns null.
Grouped a few Parameterized Tests by their type.
Constrained long lines to 80 chars.
Separated each method in test-types with a blank line.
Added test cases for methods with complex parameters to demonstrate how FsCheck can be customized to generate complex arbitrary values. The test cases use the type Version and you may read more about Arbitrary Version instances with FsCheck on http://blog.ploeh.dk/2014/03/11/arbitrary-version-instances-with-fscheck/.