Increment raylib version and so lib version number.

This should always be the number of the raylib release.
Especially when the new version is ABI incompatible the major version
should be bumped.

Using the library() function instead of shared_library() allows changing
of the library type via the default_library option.
This allows for easy change between static and dynamic library building.

Use 'meson --default-library=static builddir' to build as static, if no builddir yet exists.
Use 'mesonconf -Ddefault_library=static builddir' to change the type for
an existing builddir.