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/dialogxml/pict.cpp

@@ -76,11 +76,11 @@ void cPict::attachClickHandler(click_callback_t f) throw(){
 	}
 }
 
-void cPict::attachFocusHandler(focus_callback_t f) throw(xHandlerNotSupported){
+void cPict::attachFocusHandler(focus_callback_t) throw(xHandlerNotSupported){
 	throw xHandlerNotSupported(true);
 }
 
-bool cPict::triggerClickHandler(cDialog& me, std::string id, eKeyMod mods, location where){
+bool cPict::triggerClickHandler(cDialog& me, std::string id, eKeyMod mods){
 	if(onClick != NULL) return onClick(me,id,mods);
 	else return false;
 }
@@ -96,7 +96,7 @@ short cPict::getFormat(eFormat prop) throw(xUnsupportedProp){
 	else throw xUnsupportedProp(prop);
 }
 
-void cPict::setColour(sf::Color clr) throw(xUnsupportedProp) {
+void cPict::setColour(sf::Color) throw(xUnsupportedProp) {
 	// TODO: Colour is not supported
 }
 
@@ -419,11 +419,17 @@ ePicType& operator-= (ePicType& lhs, ePicTypeMod rhs){
 	return lhs = lhs - rhs;
 }
 
+bool operator& (ePicType lhs, ePicTypeMod rhs) {
+	return lhs == (lhs + PIC_PRESET) + rhs;
+}
+
 short cPict::animFrame = 0;
 
 std::shared_ptr<sf::Texture> cPict::getSheet(eSheetType type, size_t n) {
 	std::ostringstream sout;
 	switch(type) {
+		case NUM_SHEET_TYPES:
+			break;
 		case SHEET_TER:
 			sout << "ter" << n + 1;
 			break;