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.combat.h

@@ -26,7 +26,7 @@ short count_levels(location where,short radius);
 bool pc_near(short pc_num,location where,short radius);
 bool monst_near(short m_num,location where,short radius,short active);
 void fireball_space(location loc,short dam);
-void place_spell_pattern(effect_pat_type pat,location center,short type,bool prep_for_anim,short who_hit);
+void place_spell_pattern(effect_pat_type pat,location center,short type,short who_hit);
 void handle_item_spell(location loc,short num);
 void modify_pattern(effect_pat_type *pat,short type);
 void do_shockwave(location target);