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/scenedit/scen.keydlgs.h

@@ -10,10 +10,10 @@ void display_strings(char *text1, char *text2,
 	char *title,short sound_num,short graphic_num,short graphic_type,cDialog* parent);
 void put_choice_pics(short g_type);
 pic_num_t choose_graphic(short cur_choice,ePicType g_type,cDialog* parent);
-short choose_text_res(std::string res_list,short first_t,short last_t,short cur_choice,cDialog* parent,const char *title);
-short choose_text(eStrType list, short cur_choice, cDialog* parent,const char* title);
+short choose_text_res(std::string res_list,short first_t,short last_t,unsigned short cur_choice,cDialog* parent,const char *title);
+short choose_text(eStrType list, unsigned short cur_choice, cDialog* parent,const char* title);
 void edit_text_str(short which_str,short mode);
-void edit_spec_enc(short which_node,short mode,cDialog* parent);
+void edit_spec_enc(short which_node,short mode);
 short get_fresh_spec(short which_mode);
 void edit_spec_text(short mode,short *str1,short *str2,cDialog* parent);
 void edit_dialog_text(short mode,short *str1,cDialog* parent);