Added method to change title text color and get title text color

[michael-winkler]

This helper let the user change the tite text color via code

[quentin41500]

Thank you for posting this PR. We recommend changing the color for title, weekdays and days like so:

  <style name="CustomTextAppearance" parent="TextAppearance.AppCompat.Medium">
    <item name="android:textColor">@android:color/holo_red_dark</item>
  </style>

      app:mcv_headerTextAppearance="@style/CustomTextAppearance"
      app:mcv_dateTextAppearance="@style/CustomTextAppearance"
      app:mcv_weekDayTextAppearance="@style/CustomTextAppearance"

You can also set it programmatically:

  /**
   * @param resourceId The text appearance resource id.
   */
  public void setHeaderTextAppearance(int resourceId) {
    title.setTextAppearance(getContext(), resourceId);
  }