Merge and remove util classes

app/src/main/java/eu/kanade/tachiyomi/widget/EmptyView.kt

@@ -29,7 +29,7 @@ class EmptyView @JvmOverloads constructor(context: Context, attrs: AttributeSet?
      * @param textResource text of information view
      */
     fun show(drawable: Int, textResource: Int) {
-        image_view.setVectorCompat(drawable, context.theme.getResourceColor(android.R.attr.textColorHint))
+        image_view.setVectorCompat(drawable, context.getResourceColor(android.R.attr.textColorHint))
         text_label.text = context.getString(textResource)
         this.visibility = View.VISIBLE
     }

app/src/main/java/eu/kanade/tachiyomi/widget/ExtendedNavigationView.kt

@@ -75,7 +75,7 @@ open class ExtendedNavigationView @JvmOverloads constructor(
              */
             fun tintVector(context: Context, resId: Int): Drawable {
                 return VectorDrawableCompat.create(context.resources, resId, context.theme)!!.apply {
-                    setTint(context.theme.getResourceColor(R.attr.colorAccent))
+                    setTint(context.getResourceColor(R.attr.colorAccent))
                 }
             }
         }

app/src/main/java/eu/kanade/tachiyomi/widget/preference/LoginCheckBoxPreference.kt

@@ -8,6 +8,7 @@ import android.view.View
 import eu.kanade.tachiyomi.R
 import eu.kanade.tachiyomi.data.source.online.LoginSource
 import eu.kanade.tachiyomi.data.source.online.OnlineSource
+import eu.kanade.tachiyomi.util.getResourceColor
 import eu.kanade.tachiyomi.util.setVectorCompat
 import kotlinx.android.synthetic.main.pref_item_source.view.*
 import net.xpece.android.support.preference.CheckBoxPreference
@@ -31,7 +32,7 @@ class LoginCheckBoxPreference @JvmOverloads constructor(
             val tint = if (source.isLogged())
                 Color.argb(255, 76, 175, 80)
             else
-                Color.argb(97, 0, 0, 0)
+                context.getResourceColor(android.R.attr.textColorSecondary)
 
             holder.itemView.login.setVectorCompat(R.drawable.ic_account_circle_black_24dp, tint)
 

app/src/main/java/eu/kanade/tachiyomi/widget/preference/SwitchPreferenceCategory.kt

@@ -25,7 +25,7 @@ class SwitchPreferenceCategory @JvmOverloads constructor(
 CompoundButton.OnCheckedChangeListener {
 
     init {
-        setTitleTextColor(context.theme.getResourceColor(R.attr.colorAccent))
+        setTitleTextColor(context.getResourceColor(R.attr.colorAccent))
     }
 
     private var mChecked = false