Failed attempt to resolve Doxygen file conflicts.

Found even more stuff broken -- copied contents of
Corrade::Utility::Directory::Flags into Magnum::Context::Flags (WTF!),
asterisks in code listings... IS IT SO HARD TO FIX ONE THING AND DON'T
BREAK THOUSAND OTHERS, DAMMIT??

src/Audio/Context.h

@@ -24,7 +24,7 @@
     DEALINGS IN THE SOFTWARE.
 */
 
-/** @file
+/** @file Audio/Context.h
  * @brief Class Magnum::Audio::Context
  */
 

src/Context.h

@@ -38,6 +38,8 @@
 
 namespace Magnum {
 
+/** @todoc Resolve conflict with Audio/Context.h (Doxygen doesn't list this file) */
+
 namespace Implementation {
     struct State;
 }