Lua: 5.3 integer support: Decided that when going from Lua->C, strict integer (as opposed to number) checking is too aggressive by default and should be made a compile time option. -DSWIG_LUG_USE_STRICT_INTEGER_CHECK

You (the user) may compile with -DSWIG_LUG_USE_STRICT_INTEGER_CHECK
  to enforce stricter type checking to allow only integers and fail on numbers (floating point).
  This might be hard for projects updating from pre-Lua 5.3 projects
  because scripters may have freely mixed integers and floating point.
  So this is off by default.

The specific implementation in the non-strict case will first check lua_isinteger and then lua_isnumber. I think lua_isnumber may auto-convert types (like from strings), so that's why I don't just check lua_isnumber and assume it will catch integers too. It would be bad if Lua converted from integer to float and then convert back to integer when you get the value.
Merge branch 'lua' into Lua53IntegerAndVandalEq

* lua:
  Lua: 5.3 integer support: Decided that when going from Lua->C, strict integer (as opposed to number) checking is too aggressive by default and should be made a compile time option. -DSWIG_LUG_USE_STRICT_INTEGER_CHECK