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/tools/specials_parse.cpp

@@ -283,6 +283,7 @@ void SpecialParser::set_third(int i, ph_t, bool& pass) {
 
 std::map<size_t,cSpecial> SpecialParser::parse(std::string code) {
 	bool success = qi::parse(code.begin(), code.end(), nodes_file);
+	(void) success; // Suppress "unused parameter" warning
 	return specials;
 }
 
@@ -297,6 +298,7 @@ void SpecialParser::init_debug() {
 //	BOOST_SPIRIT_DEBUG_NODE(nodes_file);
 }
 
+void test_special_parse(std::string file); // Suppress "no prototype" warning
 void test_special_parse(std::string file) {
 	std::ostringstream code;
 	std::ifstream fin(file);