Add a basic test for Lua language

tests/data/lua.lua

@@ -0,0 +1,48 @@
+-- 48 lines 12 code 26 comments 10 blanks
+
+-- Standard comment
+
+-- Standard block comment
+--[[
+print("Hello world")
+--]]
+
+-- The following print statement isn't a commented
+---[[
+print("Hello world")
+--]]
+
+-- Another block comment
+--[=[
+We can include "]]" inside this comment
+--]=]
+
+--[==[
+We can include "]=]" inside this comment
+--]==]
+
+
+local s = [[--[[ and -- don't start comments inside multiline strings.
+A multiline string.
+It can't contain double square brackets. Instead one must write: [=[]=].
+]]
+
+local s = [=[
+Also a multiline string.
+This one can contain [[]].
+Alternatively, one may add one more equal sign between the square brackets: [==[]==]
+]=]
+
+-- Here only the first print statement is executed
+---[[
+print("Hello world 1")
+--[=[]]
+print("Hello world 2")
+--]=]
+
+-- Here only the second print statement is executed
+--[[
+print("Hello world 1")
+--[=[]]
+print("Hello world 2")
+--]=]