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

scripts/run-functional-tests.py

@@ -0,0 +1,81 @@
+# Run functional tests using lua, busted and the python client
+
+import os
+import sys
+import textwrap
+
+from lupa import LuaRuntime
+from neovim import Nvim, spawn_session
+
+
+# Extract arguments
+busted_script = sys.argv[1]
+busted_argv = sys.argv[2:]
+
+# Setup a lua state for running busted
+lua = LuaRuntime(unpack_returned_tuples=True)
+lua_globals = lua.globals()
+
+# helper to transform iterables into lua tables
+list_to_table = lua.eval('''
+function(l)
+  local t = {}
+  for i, item in python.enumerate(l) do t[i + 1] = item end
+  return t
+end
+''')
+
+dict_to_table = lua.eval('''
+function(d)
+  local t = {}
+  for k, v in python.iterex(d.items()) do t[k] = v end
+  return t
+end
+''')
+
+nvim_prog = os.environ.get('NVIM_PROG', 'build/bin/nvim')
+nvim_argv = [nvim_prog, '-u', 'NONE', '--embed']
+
+if 'VALGRIND' in os.environ:
+    log_file = os.environ.get('VALGRIND_LOG', 'valgrind-%p.log')
+    valgrind_argv = ['valgrind', '-q', '--tool=memcheck', '--leak-check=yes',
+                     '--track-origins=yes', '--suppressions=.valgrind.supp',
+                     '--log-file={0}'.format(log_file)]
+    if 'VALGRIND_GDB' in os.environ:
+        valgrind_argv += ['--vgdb=yes', '--vgdb-error=0']
+    nvim_argv = valgrind_argv + nvim_argv
+
+session = spawn_session(nvim_argv)
+nvim = Nvim.from_session(session)
+
+def nvim_command(cmd):
+    nvim.command(cmd)
+
+def nvim_feed(input, mode=''):
+    nvim.feedkeys(input)
+
+def buffer_slice(start=None, stop=None, buffer_idx=None):
+    rv = '\n'.join(nvim.buffers[buffer_idx or 0][start:stop])
+    return rv
+
+def nvim_replace_termcodes(input, *opts):
+    return nvim.replace_termcodes(input, *opts)
+
+expose = [
+    nvim_command,
+    nvim_feed,
+    nvim_replace_termcodes,
+    buffer_slice,
+    textwrap.dedent,
+]
+
+for fn in expose:
+    lua_globals[fn.__name__] = fn
+
+# Set 'arg' global to let busted parse arguments
+lua_globals['arg'] = list_to_table(busted_argv)
+
+# Read the busted script and execute in the lua state
+with open(busted_script) as f:
+    busted_setup = f.read()
+lua.execute(busted_setup)