Use move semantics for operator[] in the map.
Don't install test binaries.
Install header files to the appropriate location.
Split map constructors into two, causes issues on clang.
Add cap() and clear() methods to the map.
Remove slice comments, fix clang build.

Documentation is now external. Will be available soon when the documentation
generator is finished.
Use -O0, sadly clang doesn't support -Og yet.

And fix the _config.h file missing in the installation dir.
Add fmt library. Just a beginning.
Verbose error is now implemented.
Add basic tests for errors.
Fix a bug in detach_unsafe string method.

Also adds temporary description of the string class itself, will be moved to
the separate documentation soon. Just needed a place to store it somewhere.
Major move of headers.

The idea now is that you have one public header per namespace.
Add funcref. Class that allows you to use both function ptr and lambda.
Finalize header move by adjusting all the headers. Also rename funcref.
Additional work on the map interface.
Add strings namespace. Almost complete.
Add more licensing headers to some files.