Remove unused files.

Fixes #1522

// FREEBIE
Replace XML serializer in plaintext export

Fixes #342

- using regex pattern/matcher to escape chars below 0x0020 and
  above 0xd7ff
- using String.Replace to escape XML entities
- changed XmlPullParser from Xml.newPullParser() to
  XmlPullParserFactory parser to fix import on GB
Revert "change out key cached icon to be more unique"

This reverts commit d6d76fa95315068ab5457b23fb4908c4a8586982.
no longer load a recipient for each filter text

// FREEBIE
Merge pull request #1642 from mcginty/canonical-bunk-addresses

don't try to load recipients for each filter text