Add backspace shortcut to go back

svelte/src/filesystem/filemanager/SearchBar.svelte

@@ -105,6 +105,11 @@ const input_keyup = e => {
 		if (selected_result+1 < search_results.length) {
 			selected_result++
 		}
+	} else if (e.key === "Backspace" && search_term === "") {
+		// You can use backspace to go back to the previous page, handy if you
+		// searched for the wrong thing and want to go back
+		history.back()
+		e.preventDefault()
 	} else {
 		search()
 	}
@@ -163,7 +168,7 @@ const window_keydown = (e) => {
 			bind:this={search_bar}
 			class="term"
 			type="text"
-			placeholder="Type to search in {$nav.base.name}"
+			placeholder="Press / to search in {$nav.base.name}"
 			style="width: 100%;"
 			bind:value={search_term}
 			on:keydown={input_keydown}