Progress: restructure string project and eventially utf project.

Progress: restructure string project and eventially utf project.

This collapses much of the code from fl_string into f_string.
I have originally wanted to keep f_string source file free to help reduce recursion but the design kept leading me to deciding to do this.
The final straw was the extern const strings.

This moves all of the string related functionality that does not strictly depend on f_utf into f_string.
I expect that the fl_utf and fl_string will be merged together into fl_string.
I also expect that following these changes and the related cleanups then I will be at a good point to update and get the UTF-8 processing code in sync with the current string processing code.
That is, the f_utf_string needs to work similar to f_string types as well as have the same functions.

This collapsing of the level 1 code into level 0 code will also require an update on all appropriate dependencies (header files being included, etc..).

I also strived for more completeness in this and added many missing functions and macros.
I did not get as far as I would like, resulting in this being a Progress commit instead of an Update commit.