[clang-tidy] Add inconsistent declaration parameter name check

This is first of series of patches, porting code from my project colobot-lint,
as I mentioned recently in cfe-dev mailing list.

This patch adds a new check in readability module:
readability-inconsistent-declaration-parameter-name. I also added appropriate
testcases and documentation.

I chose readability module, as it seems it is the best place for it.

I think I followed the rules of LLVM coding guideline, but I may have missed
something, as I usually use other code formatting style.

http://reviews.llvm.org/D12462

Patch by Piotr Dziwinski!

llvm-svn: 247261