Add Google Crosextra Carlito compatibility fonts

Carlito is a sans-serif font that is metrically-compatible with
Microsoft's Calibri.

Whenever a system is lacking Calibri, Calibri may be substituted
by Carlito to obtain a fairly faithful rendition of a document
without any text needing to be reflowed.

css/fonts.css

@@ -112,6 +112,30 @@
   font-weight: normal;
   font-style: italic;
 }
+@font-face {
+  font-family: "Carlito";
+  src: url("./fonts/Carlito-Regular.ttf") format("truetype");
+  font-weight: normal;
+  font-style: normal;
+}
+@font-face {
+  font-family: "Carlito";
+  src: url("./fonts/Carlito-Bold.ttf") format("truetype");
+  font-weight: bold;
+  font-style: normal;
+}
+@font-face {
+  font-family: "Carlito";
+  src: url("./fonts/Carlito-Italic.ttf") format("truetype");
+  font-weight: normal;
+  font-style: italic;
+}
+@font-face {
+  font-family: "Carlito";
+  src: url("./fonts/Carlito-BoldItalic.ttf") format("truetype");
+  font-weight: bold;
+  font-style: italic;
+}
 @font-face {
   font-family: "Lohit Devanagari";
   src: url("./fonts/Lohit-Devanagari.ttf") format("truetype");