The hexadecimal notation is a Luajit extension which is not compatible with Lua
5.1. While Lua 5.2 does support hexadecimal sequences, it is better to target
Lua 5.1 for maximum compatibility with Luajit(which has fully compatible with
5.1 API/ABI).
The test was split into several blocks reusing the same input file. As it is
complicated to send text in different encodings and with control characters
from the test suite to nvim and back the results are written to a temp file
and loaded into the test from there.
