Use writeByte everywhere instead of having writeByte and writebyte
Call extractString instead of manually null-terminating and extracting
Call extractString instead of toChars and manually NULLing .data
Replace OutBuffer::toChars with peekString to clarify intent and avoid confusion with Object::toChars
Merge pull request #3154 from yebblies/extractstring

[cleanup] Clean up the way strings are created from `OutBuffer`