Nuke as many warnings as possible, and several globals as well

- Warnings completely suppressed for the included TinyXML and gzstream libraries
- Parentheses warnings are now errors, since there were several that looked like bugs
- Ditto for dangling else warnings

Some of these warnings were actually bugs:
- Town wandering monsters would have never spawned, because the code to do so was accidentally nested within a check for overall_mode == MODE_OUTDOORS
---> boe.monster.cpp, lines 105-137
- Monster's behaviour with respect to elemental fields did not correctly depend on their immunities (this is the same precedence issue Sylae messed up fixing in the Windows code)
---> boe.monsters.cpp, lines 345-359
- Display of damage blocked by armour appeared to be incorrect (needs verification)
---> boe.newgraph.cpp, line 1079
- Three-choice dialogs probably weren't dealing with unusual button types correctly, though that's a minor point since they aren't expected to use such buttons

osx/boe.specials.h

@@ -7,8 +7,7 @@ void use_spec_item(short item);
 void use_item(short pc,short item);
 bool use_space(location where);
 bool adj_town_look(location where);
-void PSOE(short str1a,short str1b,short str2a,short str2b,
-	short which_special,unsigned char *stuff_done_val,short where_put);
+void PSOE(short which_special,unsigned char *stuff_done_val,short where_put);
 bool damage_monst(short which_m, short who_hit, short how_much, short how_much_spec, eDamageType dam_type, short sound_type);
 void kill_monst(cCreature *which_m,short who_killed);
 void special_increase_age();