Modified ListView adapter with searchable custom headers.
Details can be found at http://simonbaeg.com/searchable-list-adapter-with-headers/
Created with the help from:
http://jsharkey.org/blog/2008/08/18/separating-lists-with-headers-in-android-09/ https://cristiantanas.wordpress.com/2015/01/14/android-listview-what-they-never-told-you-about-list-sections/