EMI/GRIM: Allow integer arguments for MakeSectorActive

The first argument of MakeSectorActive can be either a string or a
number. If a number is used by the lua call lua_isstring will also return
true (see engines/grim/lua/lapi.cpp) and so the correct code which
handles the integer case is never called.

This patch reverses the order of the tests via lua_isstring and
lua_isnumber.

In EMI this fixes the following:
- big monkey head on Monkey Island stays open even after set or setup
  change
- the lights in the bank on lucre island stay off until Guybrush turns
  them on
- shadow of Pegnose's nose is visible in close-up camera view
Merge pull request #816 from chkr-private/sector-fixes

EMI/GRIM: Allow integer arguments for MakeSectorActive