Add WKBReader::read() & WKBWriter::write() PHP bindings

Currently, only `WKBReader::readHEX()` and `WKBWriter::writeHEX()` bindings are available, but their binary counterparts `read()` and `write()` don't have PHP bindings.

This is quite annoying as consumer code has to convert WKB back and forth with `hex2bin()` and `bin2hex()`, which is quite inefficient to say the least.

This PR adds the missing bindings.