Style: added vim modeline.
Style: use macro instead of magic-number.
use lua_pushliteral for string-literals.
Merge pull request #411 from cubicdaiya/feature/ues_luapushliteral2

use lua_pushliteral for string-literals.
Merge pull request #410 from cubicdaiya/feature/use_macro

Style: use macro instead of magic-number.
Merge pull request #409 from cubicdaiya/feature/vim

Style: added vim modeline.
fixed the build failure introduced in commit 109fd454a.
config: now we also explicitly check the Lua ABI/language version in our feature test for a Lua lib.