Add initial support for custom sniffing

examples/custom-sniffer

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+
+file="$1"
+
+if [[ $file == *.pl ]]; then
+    # the default is that .pl corresponds to perl, but not here!
+    echo -n "prolog"
+fi
+
+if [[ $file == *.ts ]]; then
+    # qt translations, who knew
+    echo -n "qt-translation"
+fi
+
+# We're fine with the defaults for other types of files so we don't
+# print anything else.
+echo ""
+exit 0