Interface simplification

I big simplification of shared_library interface:
* no need in explicit `library("foo.dll")` calls
* no need in explicit `symbol("function_name")` calls
* minor fix in config file
* mutex was removed from `shared_library` class and `shred_library_impl` (does not look like it must be in there... In STL synchronization it is usually moved away from container class. Was followed the same scheme here)
*  `shred_library_impl`s were simplified, all the interface functions are implemented in `shared_library`
* function `void* get_symbol("name")` was transformed into `symbol_type& get<symbol_type>("name")`. See test/shared_library_* tests for an example of new interface.
* more operators for `shared_library`

This pull request is mainly for the discussion, it is not ready for merging yet!
I'm open for discussion. How do you like the new interface?