There is still cleanup work to be done in the headers, but this
concludes the major include-what-you-use refactoring. No functional
change is intended or expected and all tests are passing.
It is now a lot easier to see what is used from each header and work on
possible refactoring in the future.
The include-what-you-use tool is awkward to use with the current state
of the build system - and will always be difficult to use in a
multi-platform safe way. However, I hope to provide a non manual
process for running with the tool in the future.
* Move the makefiles towards a clearer arrangement
* Break circular make dependancy and start using implicit rules for most compilation
* Fix old cmake to compile again after renames
