plass always did a `got add $file' before committing changes. However, this leads to a possibly misleading "file has unexpected status" error being printed to stderr. Instead, `got add $file' only when the file is new.

Now it always deletes the temporary file.

inline (with tweaks) writepass, it's redundant to have. While here also read/write blockwise instead that of linewise.

There's no real reason to have this variable, there's only one `got' usually and people are better off putting it somewhere in $PATH. Retain PLASS_GPG as there seem to be a little issue with gpg vs gpg2 so the knob may be useful in practice.