add property based tests with FsCheck

[vilinski]

originally the bug #213 was found using the FsCheck in my internal project. This will be hopefully fixed soon thanks to PR #220 from @RamType-0

Adding FsCheck proposed since property based tests are:

• more poverful - covering not expected range cases too.
• easier to handle than Theory with InlineData - you don't need to write the input values manually
• especially useful for testing serialize/deserialize loops - generates input for any types and data structures