ref #9280
Introduce the `vim.compat` module, to help environments with system Lua
5.2+ run the build/tests. Include the module implicitly in all tests.
ref #8677
legacy `vim` module:
beep
buffer
command
dict
eval
firstline
lastline
line
list
open
type
window
Hope this will make people using feed_command less likely: this hides bugs.
Already found at least two:
1. msgpackparse() will show internal error: hash_add() in case of duplicate
keys, though it will still work correctly. Currently silenced.
2. ttimeoutlen was spelled incorrectly, resulting in option not being set when
expected. Test was still functioning somehow though. Currently fixed.
It is otherwise impossible to determine which test failed sanitizer/valgrind
check. test/functional/helpers.lua module return was changed so that tests which
do not provide after_each function to get new check will automatically fail.
