Remove getFileType() and getChangeType() from DifferentialChangeset

Summary:
These are explicit copies of implicitly-generated Lisk methods.

See brief discussion in rPdec8bac3a3af6065166d485db80fffa70dc2abe3.

Test Plan: Looked at a diff in Differential.

Reviewers: vrana, btrahan

Reviewed By: vrana

CC: aran

Differential Revision: https://secure.phabricator.com/D2283

src/applications/differential/storage/changeset/DifferentialChangeset.php

@@ -49,14 +49,6 @@ final class DifferentialChangeset extends DifferentialDAO {
     return $this->getAddLines() + $this->getDelLines();
   }
 
-  public function getFileType() {
-    return $this->fileType;
-  }
-
-  public function getChangeType() {
-    return $this->changeType;
-  }
-
   public function attachHunks(array $hunks) {
     assert_instances_of($hunks, 'DifferentialHunk');
     $this->hunks = $hunks;