Now charset to be used can be specified at runtime, instead of compile time.
Due to this change, charset specific ports are being removed, and pTeX now consists of two ports: ptex-base and ptex.
Ptex-base is what used to be ptex-common, which installs non-Japanese portion of the system, and ptex is what used to be the charset specific portion, which installs Japanese specific files.
Thus, ptex-common and ptex-euc are renamed to ptex-base and ptex respectively, and ptex-jis and ptex-sjis are being removed.
