Merge pull request #5 from froj/master

Abstraction for mutexes.
Rework documentation.
Added a comment to undocumented function.

Although the name is obvious, I like comments.
Merge pull request #8 from antoinealb/master

Rework documentation
Added clang to continuous integration.
Switched project type to C++ to have clang++.
Merge pull request #13 from antoinealb/add-clang

Added clang to continuous integration.
Fix issue #6 (semaphore max_count).
Merge pull request #15 from antoinealb/issue-6-max_count

Fix issue #6 (semaphore max_count).
I think we all agreed that this was the right thing to do (for now).
non-blocking mutex pend
non-blocking semaphore pend
test for non-blocking semaphore
completed the test for non-blocking mutexes