Add epub icon with id file-epub

Used https://github.com/kjodle/epub-icon for the inner icon

Compiled files not included.

Address #131

src/icons/icons.yml

@@ -7196,3 +7196,11 @@ icons:
     url:        gitea.io
     categories:
       - Brand Icons
+
+  - name:       EPUB
+    id:         file-epub
+    unicode:    f320
+    created:    1.1
+    categories:
+      - Web Application Icons
+      - File Type Icons

src/icons/svg/epub.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1536 1792" height="1792" width="1536">
+    <path d="M722.197 1403.92l-343.154-343.182 343.154-343.133L836.591 831.98l-228.788 228.759 114.387 114.394L1065.343 832 766.418 533.072c-24.41-24.43-64.002-24.43-88.432 0l-483.481 483.48c-24.41 24.411-24.41 64.003 0 88.434l483.488 483.467c24.43 24.43 64.022 24.43 88.432 0l483.489-483.467c24.408-24.43 24.408-64.023 0-88.432l-70.19-70.168z"/>
+    <path d="M1466.915 380c37 37 68 111 68 164v1152c0 53-43 96-96 96h-1344c-53 0-96-43-96-96V96c0-53 43-96 96-96h896c53 0 127 31 164 68zm-444-244v376h376c-6-17-15-34-22-41l-313-313c-7-7-24-16-41-22zm384 1528V640h-416c-53 0-96-43-96-96V128h-768v1536z"/>
+</svg>