* Add #include preprocessing to filamat and matc
* Update RELEASE_NOTES
* Fix RELEASE_NOTES
* Use final instead of virtual / override
* Clarify comments
* Use pure virtual for includer functions
* Use a callback instead of an interface
* Rename Includer.h to IncludeCallback.h
* Update comment
In a lot of case the StaticString hash can be computed a compile time,
so we now take advantage of that.
Removed StaticString(const char*) ctor, and replaced it with a
StaticString::make() method.
Fixed a couple wrong uses of the old StaticString(const char*) ctor.