Fix #253, use user defined TypeHandlers over internal implementations.

[adminnz]

basically SqlMapper was using its own internal IEnumerable type handling even if the user has defined their own type handler for IEnumerable types (e.g. List).

I've switched the order so it will check if the user has defined a type handler for this, and then use the IEnumerable implementation.
Also I added two tests, to DapperTests NET40 with a very simple List TypeHandler implementation that will read Strings into a List by splitting the string comma. And also will use join a list by comma and set a parameter from a List.

[espenekvang]

Any indications on when this pullrequest can be merged in? We have implemented a custom typehandler but SetValue is never called.

[jhovgaard]

Spent time "bug fixing" this too. +1 for merge.

[RufusJWB]

I have the same problem and it would be great, if it could be fixed.

[klesh]

Support +1
It would be great to fix this problem.

[johandanforth]

I merged the fix and the tests provided by @adminnz . Would you all please test things a bit and give feedback before I update Nuget as well? I normally only work with the Contrib parts but this one seems pretty obvious to merge in so...Thanks for your patience. ping @espenekvang @jhovgaard @RufusJWB @klesh

[klesh]

Hi, Johan, thanks for your help.
I checked the test case and ran it, everything seems alright...
All two test cases are passed. @johandanforth

[johandanforth]

Great. I'm closing this one then.

[RufusJWB]

I couldn't help testing, but I highly appreciate your quick response! Thank you very much!

[jhovgaard]

Thanks for the merge! Works here.