This fixes:
```
[Warning] SerialBase.h@351,22: 'mbed::SerialBase::_flow2' will be initialized after [-Wreorder]
[Warning] SerialBase.h@343,22: 'bool mbed::SerialBase::_rx_enabled' [-Wreorder]
[Warning] SerialBase.cpp@26,1: when initialized here [-Wreorder]
```
by using C++11 style initializer for SerialBase
Kudos to Kevin Bracey, as her his suggestion - we can drop the initializer
list if we just set the values directly in the SerialBase.h. No need to
worry about the "right order" after that.
Separate drivers, events, and rtos internal APIs from public APIs.
* Move source files to source subdirs
* Move internal headers to internal subdirs
* Add Doxygen comments for documenting internal and public APIs
* Remove source code from header files in order to remove include pre-processor directives
that included header files not directly used by said header files
* Explicitly include header files instead of implicit inclusions via third-party header files.
Release Notes
This will break user code that was using an internal API as the internal header files have been moved.
This will only break if the user was including the header file using a namespace (i.e #include "foo/bar.h" instead of #include "bar.h"
Janne Kiiskila
Sebastian Stockhammer
Hugues Kamba