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/classes/monster.h

@@ -97,7 +97,7 @@ public:
 	struct cAttack{
 		unsigned char dice, sides, type;
 		// TODO: Remove the need for these operators by changing the code that uses them
-		operator int();
+		operator int() const;
 		cAttack& operator=(int n);
 	};
 	struct cAbility{
@@ -189,5 +189,5 @@ std::ostream& operator << (std::ostream& out, eRace& e);
 std::istream& operator >> (std::istream& in, eRace& e);
 std::ostream& operator << (std::ostream& out, eMonstAbil& e);
 std::istream& operator >> (std::istream& in, eMonstAbil& e);
-std::ostream& operator<<(std::ostream& out, cMonster::cAttack& att);
+std::ostream& operator<<(std::ostream& out, const cMonster::cAttack& att);
 #endif