Merge branch 'svn-fe' of git://repo.or.cz/git/jrn into jn/svn-fe

Merge branch 'svn-fe' of git://repo.or.cz/git/jrn into jn/svn-fe

This simplifies svn-fe a great deal and fulfills a longstanding wish:
support for dumps with deltas in them, and incremental imports.

The cost is that commandline usage of the svn-fe tool becomes a little
more complicated since it no longer keeps state itself but instead reads
blobs back from fast-import in order to copy them between revisions and
apply deltas to them.

Also removes a couple of custom data structures and replaces them with
strbufs like other parts of Git.

* 'svn-fe' of git://repo.or.cz/git/jrn: (32 commits)
  vcs-svn: reset first_commit_done in fast_export_init
  vcs-svn: do not initialize report_buffer twice
  vcs-svn: avoid hangs from corrupt deltas
  vcs-svn: guard against overflow when computing preimage length
  vcs-svn: cap number of bytes read from sliding view
  test-svn-fe: split off "test-svn-fe -d" into a separate function
  vcs-svn: implement text-delta handling
  vcs-svn: let deltas use data from preimage
  vcs-svn: let deltas use data from postimage
  vcs-svn: verify that deltas consume all inline data
  vcs-svn: implement copyfrom_data delta instruction
  vcs-svn: read instructions from deltas
  vcs-svn: read inline data from deltas
  vcs-svn: read the preimage when applying deltas
  vcs-svn: parse svndiff0 window header
  vcs-svn: skeleton of an svn delta parser
  vcs-svn: make buffer_read_binary API more convenient
  vcs-svn: learn to maintain a sliding view of a file
  Makefile: list one vcs-svn/xdiff object or header per line
  vcs-svn: avoid using ls command twice
  ...

Conflicts:
	Makefile
	contrib/svn-fe/svn-fe.txt