Eschew using PNGs in favor of SVGs

By eliminating the `mogrify` processing dependency, downloading the most
recent set of icons goes from hours to well under a minute. SVGs are
also superior for scaling on larger cards. A few `.png` files remain,
however (namely those not from game-icons.net in `…/classes/…`).

Because processing is now so quick, this also removes all icon copies
from this repo. This saves a ton of space, but imposes a requirement on
cloners to run `node ./resources/tools/update-icons.js` instead of
relying on any checked-in snapshot.

Fixes #111.
Depends on #146.

.gitignore

@@ -1,5 +1,11 @@
-/node_modules
-/generator/js/*.map
+/generator/css/icons.css
+/generator/img/*.png
+/generator/img/*.svg
+/generator/img/license.txt
 /generator/js/*.d.ts
-/temp
+/generator/js/*.map
+/generator/js/icons.js
+/node_modules/
+/package-lock.json
 /temp.zip
+/temp/

generator/css/custom-icons.css

@@ -1,34 +1,34 @@
-.icon-custom-armor-light { background-image: url(../img/leather-vest.png);}
-.icon-custom-armor-medium { background-image: url(../img/lamellar.png);}
-.icon-custom-armor-heavy { background-image: url(../img/breastplate.png);}
-.icon-custom-shield { background-image: url(../img/round-shield.png);}
+.icon-custom-armor-light { background-image: url(../img/leather-vest.svg);}
+.icon-custom-armor-medium { background-image: url(../img/lamellar.svg);}
+.icon-custom-armor-heavy { background-image: url(../img/breastplate.svg);}
+.icon-custom-shield { background-image: url(../img/round-shield.svg);}
 
-.icon-custom-potion { background-image: url(../img/drink-me.png);}
-.icon-custom-light { background-image: url(../img/candle-flame.png);}
-.icon-custom-flask { background-image: url(../img/fizzing-flask.png);}
-.icon-custom-vial { background-image: url(../img/chemical-drop.png);}
-.icon-custom-poison { background-image: url(../img/poison-bottle.png);}
-.icon-custom-trap { background-image: url(../img/wolf-trap.png);}
-.icon-custom-item { background-image: url(../img/knapsack.png);}
-.icon-custom-wand { background-image: url(../img/crystal-wand.png);}
-.icon-custom-swords { background-image: url(../img/crossed-swords.png);}
-.icon-custom-arrows { background-image: url(../img/target-arrows.png);}
-.icon-custom-swordarrow { background-image: url(../img/mixed-swords.png);}
+.icon-custom-potion { background-image: url(../img/drink-me.svg);}
+.icon-custom-light { background-image: url(../img/candle-flame.svg);}
+.icon-custom-flask { background-image: url(../img/fizzing-flask.svg);}
+.icon-custom-vial { background-image: url(../img/chemical-drop.svg);}
+.icon-custom-poison { background-image: url(../img/poison-bottle.svg);}
+.icon-custom-trap { background-image: url(../img/wolf-trap.svg);}
+.icon-custom-item { background-image: url(../img/knapsack.svg);}
+.icon-custom-wand { background-image: url(../img/crystal-wand.svg);}
+.icon-custom-swords { background-image: url(../img/crossed-swords.svg);}
+.icon-custom-arrows { background-image: url(../img/target-arrows.svg);}
+.icon-custom-swordarrow { background-image: url(../img/mixed-swords.svg);}
 
-.icon-custom-spell { background-image: url(../img/white-book.png);}
-.icon-custom-spell-0 { background-image: url(../img/white-book-0.png);}
-.icon-custom-spell-1 { background-image: url(../img/white-book-1.png);}
-.icon-custom-spell-2 { background-image: url(../img/white-book-2.png);}
-.icon-custom-spell-3 { background-image: url(../img/white-book-3.png);}
-.icon-custom-spell-4 { background-image: url(../img/white-book-4.png);}
-.icon-custom-spell-5 { background-image: url(../img/white-book-5.png);}
-.icon-custom-spell-6 { background-image: url(../img/white-book-6.png);}
-.icon-custom-spell-7 { background-image: url(../img/white-book-7.png);}
-.icon-custom-spell-8 { background-image: url(../img/white-book-8.png);}
-.icon-custom-spell-9 { background-image: url(../img/white-book-9.png);}
-.icon-custom-spell-holy { background-image: url(../img/white-book-cd.png);}
-.icon-custom-spell-runes { background-image: url(../img/book-cover.png);}
+.icon-custom-spell { background-image: url(../img/white-book.svg);}
+.icon-custom-spell-0 { background-image: url(../img/white-book-0.svg);}
+.icon-custom-spell-1 { background-image: url(../img/white-book-1.svg);}
+.icon-custom-spell-2 { background-image: url(../img/white-book-2.svg);}
+.icon-custom-spell-3 { background-image: url(../img/white-book-3.svg);}
+.icon-custom-spell-4 { background-image: url(../img/white-book-4.svg);}
+.icon-custom-spell-5 { background-image: url(../img/white-book-5.svg);}
+.icon-custom-spell-6 { background-image: url(../img/white-book-6.svg);}
+.icon-custom-spell-7 { background-image: url(../img/white-book-7.svg);}
+.icon-custom-spell-8 { background-image: url(../img/white-book-8.svg);}
+.icon-custom-spell-9 { background-image: url(../img/white-book-9.svg);}
+.icon-custom-spell-holy { background-image: url(../img/white-book-cd.svg);}
+.icon-custom-spell-runes { background-image: url(../img/book-cover.svg);}
 
-.icon-custom-class-arcane { background-image: url(../img/robe.png);}
-.icon-custom-class-cleric { background-image: url(../img/holy-symbol.png);}
-.icon-custom-class-rogue { background-image: url(../img/cloak-dagger.png);}
+.icon-custom-class-arcane { background-image: url(../img/robe.svg);}
+.icon-custom-class-cleric { background-image: url(../img/holy-symbol.svg);}
+.icon-custom-class-rogue { background-image: url(../img/cloak-dagger.svg);}