* Change Doxygen groups structure, splitting first by Public/Internal
This commit also does the following:
* groups the documentation of related API
* moves `events/internal/equeue.h` to `events/equeue.h`
* merges `events/source/README.md` to `events/README.md`
Also includes:
* rename `mbed_sleep_manager.c` to `mbed_power_mgmt.c` to match its
header file
* create Doxygen groups for public and internal APIs
* use relative path to include header files where inconsistent
* update references to internal APIs throughout libraries
* update the copyright year for all modified files
Turn the compile time error issued when a NonCopyable resource is copied
into a compile time and runtime warning.
If the application is compiled with the debug profile the compile time
error remains.
The compile time error can be enforced by setting the library option
force-non-copyable-error to true.