Implement editing dialogs for individual monster abilities

Changes to game:
- Permanent martyr's shield is now customizable - extra1 is per-mille chance to activate each time damage is taken, and extra2 is percent of damage taken to apply to attacker
- Absort spells is now customizable - extra1 is per-mille chance to activate each time damage is taken or a magic effect is applied, and extra2 is how much hp to gain from non-damaging magic effects
- Splits ability is now customizable - extra1 is per-mille chance of splitting each time damage is taken
- Special node ability is now called before the monster tries its normal attack, and multiple monsters can use them per round (though each can only use theirs once)
- Fix issue with breath weapons and icy touch abilities conflicting (legacy import issue)
- Add two variations of the summoning ability - summon according to summoning level (like the spells), or summon a random creature of a particular species
- Fix touch abilities using the range as chance to use

Changes to dialog engine:
- Fix tab order handling to exclude fields that are currently hidden
- Add method to retrieve the parameter passed to toast(), as a quick way to distinguish between the user clicking OK or Cancel after run() has exited
- Fix hidden fields being drawn anyway
- Fix setting stack page sometimes crashing if the current page was invalid due to earlier reducing the page count to 0

src/scenedit/scen.core.h

@@ -4,7 +4,7 @@ class cDialog;
 void edit_custom_pics_types();
 short edit_ter_type(ter_num_t which_ter);
 short edit_monst_type(short which_monst);
-cMonster edit_monst_abil(cMonster starting_record,short parent_num);
+cMonster edit_monst_abil(cMonster starting_record,short which_monst,cDialog& parent);
 short edit_item_type(short which_item);
 cItem edit_item_abil(cItem starting_record,short parent_num);
 void edit_spec_item(short which_item);