Query instance for toot character limit (#571)

* Query instance for toot character limit
Fixes #393

* Move maximumTootCharacters to instance field

* Add caching for maximum toot characters, expanding on the emoji list storage

* Update formatting per review feedback

* Fix compose activity tests

* Rename mastodon api point for nicer interaction with kotlin

* Default emoji list to empty list instead of null, to appease json converters in failure cases

* Use empty list helper

* Fix database migration

app/src/main/java/com/keylesspalace/tusky/entity/Instance.kt

@@ -0,0 +1,46 @@
+/* Copyright 2018 Levi Bard
+ *
+ * This file is a part of Tusky.
+ *
+ * This program is free software; you can redistribute it and/or modify it under the terms of the
+ * GNU General Public License as published by the Free Software Foundation; either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Tusky is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+ * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with Tusky; if not,
+ * see <http://www.gnu.org/licenses>. */
+
+package com.keylesspalace.tusky.entity
+
+import com.google.gson.annotations.SerializedName
+import java.util.*
+
+data class Instance (
+        val uri: String,
+        val title: String,
+        val description: String,
+        val email: String,
+        val version: String,
+        val urls: Map<String,String>,
+        val stats: Map<String,Int>?,
+        val thumbnail: String?,
+        val languages: List<String>,
+        @SerializedName("contact_account") val contactAccount: Account,
+        @SerializedName("max_toot_chars") val maxTootChars: Int?
+) {
+    override fun hashCode(): Int {
+        return uri.hashCode()
+    }
+
+    override fun equals(other: Any?): Boolean {
+        if (other !is Instance) {
+            return false
+        }
+        val instance = other as Instance?
+        return instance?.uri.equals(uri)
+    }
+}
+