GRIM/EMI: Count pause/unpause calls of LUA scripts

Scripts that have explicitly been paused must not be resumed when
pause_scripts and unpause_scripts are called, e.g. when opening the
inventory, pausing the game or changing sets.

This patch splits the existing paused flag in two separate ones:
 - LState::all_paused is controlled by pause/unpause_scripts (plural)
 - LState::paused is controlled by pause/unpause_script (singular)

For compatibility with Grim savegames both flags are stored in a single
byte, with bit 0 having the same meaning as the former boolean.
Merge pull request #784 from inguin/emi-pause-scripts

GRIM/EMI: Count pause/unpause calls of LUA scripts