Rename buffer functions in lexer
Rename buffer functions in lexer

This commit renames the two functions which check the state of the
input buffer and the token buffer to make their meaning a little
less obscure.

prv_ensure_buffer -> prv_ensure_input
prv_ensure_token_buffer -> prv_check_token_buffer

Signed-off-by: Mark Ryan <88ffc4093c40652fbbf052f026a8b6147509f0aa@gmail.com>

markdryan/subtilis,markdryan/subtilis