Aim for 8 pointers on each struct, wich exceptions:
- 12 pointers for already crowded/important ones
- 4 pointers for empty ones that are used for proxies; we are
unlikely to add any virtual methods on these classes ever
* Use custom_target() instead of configured shell scripts
* Do not copy all the .rst files in the build directory
* Setup dependencies between targets
* Tidy up dependencies lookup
* Remove unused files
* Upgrade Doxyfile to the latest version and cleanup used options
