test: Replace vroom by lua/busted for functional tests

The 'lupa' python package provides a simple way to seamless integrate lua and
python code.

This commit replaces vroom by a python script that exposes the 'neovim' package
to a lua state, and invokes busted to run functional tests. This is a temporary
solution that will enable writing functional tests using lua/bused while a lua
client library is not available.

The reason for dropping vroom is flexibility: Lua/busted has a nice DSL-style
syntax while also providing the customization power of a full programming
language. Another reason is to use a single framework for unit/functional tests.

Two other changes were performed in this commit:

- Instead of "gcc-unittest/gcc-ia32", the travis builds for gcc are now
  identified by "gcc/gcc-32". They will run unit/functional tests for both 64
  and 32 bits.
- Old integration tests(in src/nvim/testdir) are now ran by the 'oldtest' target

test/functional/helpers.lua

@@ -0,0 +1,84 @@
+local function clear()
+  nvim_command('call BeforeEachTest()')
+end
+
+local function feed(...)
+  for _, v in ipairs({...}) do
+    nvim_feed(nvim_replace_termcodes(dedent(v)))
+  end
+end
+
+local function rawfeed(...)
+  for _, v in ipairs({...}) do
+    nvim_feed(dedent(v), 'nt')
+  end
+end
+
+local function insert(...)
+  nvim_feed('i', 'nt')
+  rawfeed(...)
+  nvim_feed(nvim_replace_termcodes('<ESC>'), 'nt')
+end
+
+local function execute(...)
+  for _, v in ipairs({...}) do
+    if v:sub(1, 1) ~= '/' then
+      -- not a search command, prefix with colon
+      nvim_feed(':', 'nt')
+    end
+    nvim_feed(v, 'nt')
+    nvim_feed(nvim_replace_termcodes('<CR>'), 'nt')
+  end
+end
+
+local function expect(contents, first, last, buffer_index)
+  return assert.are.same(dedent(contents),
+                         buffer_slice(first, last, buffer_idx))
+end
+
+rawfeed([[:function BeforeEachTest()
+  set all&
+  redir => groups
+  silent augroup
+  redir END
+  for group in split(groups)
+    exe 'augroup '.group
+    autocmd!
+    augroup END
+  endfor
+  autocmd!
+  tabnew
+  let curbufnum = eval(bufnr('%'))
+  redir => buflist
+  silent ls!
+  redir END
+  let bufnums = []
+  for buf in split(buflist, '\n')
+    let bufnum = eval(split(buf, '[ u]')[0])
+    if bufnum != curbufnum
+      call add(bufnums, bufnum)
+    endif
+  endfor
+  if len(bufnums) > 0
+    exe 'silent bwipeout! '.join(bufnums, ' ')
+  endif
+  silent tabonly
+  for k in keys(g:)
+    exe 'unlet g:'.k
+  endfor
+  filetype plugin indent off
+  mapclear
+  mapclear!
+  abclear
+  comclear
+endfunction
+]])
+
+return {
+  clear = clear,
+  rawfeed = rawfeed,
+  insert = insert,
+  feed = feed,
+  execute = execute,
+  expect = expect 
+}