Fix bit32 conversion issues for Lua 5.1 on 32 bit

The default unsigned conversion procedure from upstream using
`lua_Integer` as an intermediate value fails if `lua_Integer` has only
32 bits (as is the case on 32 bit Lua 5.1). This fix uses a `lua_Number`
(hopefully double) as intermediate value in those cases.

Fix repository name in rockspec

Make it usable on Lua 5.4

Fix feature test for C11 Annex K (strerror_s).

Fixes lunarmodules#41.

Merge pull request lunarmodules#38 from ThePhD/warnings/vcxx

fix VC warnings for integer down-conversions to char

Add rockspec for new minor release.

Add rockspec for new minor release.

luaL_checkstack accepts NULL message.

Fix warnings emitted by luacheck.

add rockspec for pending 0.1 release