Streamline versioning APIs for the various FFI bindings (and embedded C API bindings)

[rdw-software]

Currently, most of the FFI bindings export a function version() which returns a semantic version string - except for uv.

For consistency and in order to allow checking for major version updates more easily, this could be changed:

• Either version and version_string are implemented for all relevant libraries
• Or the uv export could be renamed (version returns the string and version_string becomes version_no)
• Alternatively, version could return a number (three or four return values, for major/minor/patch)
• In this case, version_no could return the combined number (although it's somewhat obsolete)
• And optionally, version_string could return the stringified version

Either way, the result should be consistent. Since git describe is used by some, version_string is likely the common denominator?