Refactored code out of FileHeader to facilitate rename detection Refactored a superclass out of FileHeader called DiffEntry that holds the more general data from FileHeader that is useful in rename detection (old/new Ids, modes, names, as well as changeType and score). FileHeader is now a DiffEntry that adds Hunks, parsing abilities, etc. Change-Id: I8398728cd218f8c6e98f7a4a7f2f342391d865e4