Make `nextnextch()` more closely resemble `nextch()`.
Make `nextnextch()` more closely resemble `nextch()`.

graydon/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,graydon/rust,GBGamer/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,graydon/rust,graydon/rust,aidancully/rust